Built-in Macro Functions

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Built-in Macro Functions

A [ Top ]

abs(n)
Returns the absolute value of n.

acos(n)
Returns the inverse cosine (in radians) of n.

Array Functions
These functions operate on arrays. Refer to the ArrayFunctions macro for examples.

Array.concat(array1, array2) - Returns a new array created by joining two or more arrays or values (examples).
Array.copy(array) - Returns a copy of array.
Array.deleteValue(array, value) - Returns a version of array where all numeric or string elements in the array that contain value have been deleted (examples).
Array.deleteIndex(array, index) - Returns a version of array where the element with the specified index has been deleted.
Array.fill(array, value) - Assigns the specified numeric value to each element of array.
Array.filter(array, filter) Returns an array containing the elements of 'array' that contain 'filter', where 'array' is an array of strings. Enclose the filter in parans to do regular expression matching. Requires 1.53f.
Array.findMaxima(array, tolerance) - Returns an array holding the peak positions (sorted with descending strength). 'Tolerance' is the minimum amplitude difference needed to separate two peaks. With v1.51n and later, there is an optional 'edgeMode' argument: 0=include edges, 1=exclude edges(default), 2=circular array. Examples.
Array.findMinima(array, tolerance) - Returns an array holding the minima positions.
Array.fourier(array, windowType) - Calculates and returns the Fourier amplitudes of array. WindowType can be "none", "Hamming", "Hann", or "flat-top", or may be omitted (meaning "none"). See the TestArrayFourier macro for an example and more documentation.
Array.getSequence(n) - Returns an array containing the numeric sequence 0,1,2...n-1.
Array.getStatistics(array, min, max, mean, stdDev) - Returns the min, max, mean, and stdDev of array, which must contain all numbers.
Array.print(array) - Prints the array on a single line.
Array.rankPositions(array) - Returns, as an array, the rank position indexes of array, starting with the index of the smallest value (example).
Array.resample(array, len) - Returns an array which is linearly resampled to a different length.
Array.reverse(array) - Reverses (inverts) the order of the elements in array.
Array.show(array) - Displays the contents of array in a window.
Array.show("title", array1, array2, ...) - Displays one or more arrays in a Results window (examples). If title (optional) is "Results", the window will be the active Results window, otherwise, it will be a dormant Results window (see also IJ.renameResults). If title ends with "(indexes)", a 0-based Index column is shown. If title ends with "(row numbers)", the row number column is shown.
Array.slice(array, start, end) - Extracts a part of an array and returns it. (examples).
Array.sort(array) - Sorts array, which must contain all numbers or all strings. String sorts are case-insensitive.
Array.sort(array1, array2, array3...) - Sorts multiple arrays, where all the arrays adopt the sort order of array1 (example).
Array.trim(array, n) - Returns an array that contains the first n elements of array.
Array.rotate(array, d) - Rotates the array elements by 'd' steps (positive 'd' = rotate right). Requires 1.51n. Examples.
Array.getVertexAngles(xArr, yArr, arm) - From a closed contour given by 'xArr', 'yArr', an array is returned holding vertex angles in degrees (straight=0, convex = positive if contour is clockwise). Set 'arm'=1 to calculate the angle from the closest vertex points left and right, or use arm>1 for more distant neighbours and smoother results. Requires 1.51n. Examples.
asin(n)
Returns the inverse sine (in radians) of n.

atan(n)
Calculates the inverse tangent (arctangent) of n. Returns a value in the range -PI/2 through PI/2.

atan2(y, x)
Calculates the inverse tangent of y/x and returns an angle in the range -PI to PI, using the signs of the arguments to determine the quadrant. Multiply the result by 180/PI to convert to degrees.

autoUpdate(boolean)
If boolean is true, the display is refreshed each time lineTo(), drawLine(), drawString(), etc. are called, otherwise, the display is refreshed only when updateDisplay() is called or when the macro terminates.

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beep()
Emits an audible beep.

bitDepth()
Returns the bit depth of the active image: 8, 16, 24 (RGB) or 32 (float).

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calibrate(value)
Uses the calibration function of the active image to convert a raw pixel value to a density calibrated value. The argument must be an integer in the range 0-255 (for 8-bit images) or 0-65535 (for 16-bit images). Returns the same value if the active image does not have a calibration function.

call("class.method", arg1, arg2, ...)
Calls a public static method in a Java class, passing an arbitrary number of string arguments, and returning a string. Refer to the CallJavaDemo macro and the ImpProps plugin for examples.

call("class.method")
Calls a public static no-argument method in a Java class and returns a string.

changeValues(v1, v2, v3)
Changes pixels in the image or selection that have a value in the range v1-v2 to v3. For example, changeValues(0, 5, 5) changes all pixels less than 5 to 5, and changeValues(0x0000ff, 0x0000ff, 0xff0000) changes all blue pixels in an RGB image to red. In ImageJ 1.52d or later, use changeValues(NaN, NaN, value) to replaces NaN values.

charCodeAt(string, index)
Returns the Unicode value of the character at the specified index in string. Index values can range from 0 to lengthOf(string). Use the fromCharCode() function to convert one or more Unicode characters to a string.

close()
Closes the active image. This function has the advantage of not closing the "Log" or "Results" window when you meant to close the active image. Use run("Close") to close non-image windows.

close(pattern)
Closes windows whose title matches 'pattern', which can contain the wildcard characters '*' (matches any character sequence) and '?' (matches single character). For example, close("Histo*") could be used to dispose all histogram windows. Non-image windows like "Roi Manager" have to be specified without wildcards. For text windows, wildcards are allowed if 'pattern' ends with ".txt", ".ijm", ".js" etc. Use close("*") to close all image windows. Use close(pattern, "keep") to not close text or image windows with changes. If 'pattern' is "\\Others", all images except the front image are closed. The most recent macro window is never closed.

close("*")
Closes all image windows.

close("\\Others")
Closes all images except for the front image.

Color Functions
Functions for working with colors, available in ImageJ 1.53h and later. Color.set(string)
Sets the drawing color, where 'string' is "red", "blue", etc., or a hex value like "#ff0000".
Color.set(value)
Sets the drawing color. For 8 bit images, 0<=value<=255. For 16 bit images, 0<=value<=65535. With RGB images, use hex constants (e.g., 0xff0000 for red).
Color.setForeground(string)
Sets the foreground color, where 'string' is "red", "blue", etc., or a hex value like "#ff0000".
Color.setForegroundValue(value)
Sets the foreground color to grayscale, where 'value' is a number between 0 and 255.
Color.setBackground(string)
Sets the background color, where 'string' is "red", "blue", etc., or a hex value like "#ff0000".
Color.setBackgroundValue(value)
Sets the background color to grayscale, where 'value' is a number between 0 (black) and 255 (white).
Color.setForeground(r, g, b)
Sets the foreground color, where r, g, and b are >= 0 and <= 255.
Color.setBackground(r, g, b)
Sets the background color, where r, g, and b are >= 0 and <= 255.
Color.foreground
Returns the foreground color as a string, for example "red" or "#ff0000".
Color.background
Returns the background color as a string, for example "cyan" or "#00ffff".
Color.toString(r, g, b)
Converts an r,g,b color to a string.
Color.toArray(string)
Converts a color (e.g., "red" or "#ff0000") to a three element array.
Color.getLut(reds, greens, blues)
Returns three arrays containing the red, green and blue intensity values from the current lookup table. See the LookupTables macros for examples.
Color.setLut(reds, greens, blues)
Creates a new lookup table and assigns it to the current image. Three input arrays are required, each containing 256 intensity values.
Color.wavelengthToColor(wavelength)
Converts a wavelength (380-750 nm) into a color in string format (e.g., "#0031ff"). See also: Help>Examples>Plots>Plot With Spectrum.
cos(angle)
Returns the cosine of an angle (in radians).

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d2s(n, decimalPlaces)
Converts the number n into a string using the specified number of decimal places. Uses scientific notation if 'decimalPlaces is negative. Note that d2s stands for "double to string".

debug(arg)
Calls the macro debugger, where 'arg' is "break" (the default), "run", "trace", "fast-trace", "dump" or "throw". Call debug("dump") to display the contents of the symbol table, the tokenized macro code and the variable stack. Call debug("throw") to display an example "Exception" window.

Dialog.create("Title")
Creates a modal dialog box with the specified title, or use Dialog.createNonBlocking("Title") to create a non-modal dialog. Call Dialog.addString(), Dialog.addNumber(), etc. to add components to the dialog. Call Dialog.show() to display the dialog and Dialog.getString(), Dialog.getNumber(), etc. to retrieve the values entered by the user. Refer to the DialogDemo macro for an example.

Dialog.createNonBlocking("Title") - Creates a non-modal dialog box with the specified title.
Dialog.addMessage(string) - Adds a message to the dialog. The message can be broken into multiple lines by inserting new line characters ("\n") into the string.
Dialog.addMessage(string, fontSize, fontColor) - Adds a message to the dialog using a specified font size and color (example). The message can be broken into multiple lines by inserting new line characters ("\n") into the string. The 'fontSize' and 'fontColor' arguments are optional.
Dialog.addString(label, initialText) - Adds a text field to the dialog, using the specified label and initial text.
Dialog.addString(label, initialText, columns) - Adds a text field to the dialog, where columns specifies the field width in characters.
Dialog.addNumber(label, default) - Adds a numeric field to the dialog, using the specified label and default value.
Dialog.addNumber(label, default, decimalPlaces, columns, units) - Adds a numeric field, using the specified label and default value. DecimalPlaces specifies the number of digits to right of decimal point, columns specifies the the field width in characters and units is a string that is displayed to the right of the field.
Dialog.addSlider(label, min, max, default) - Adds a slider controlled numeric field to the dialog, using the specified label, and min, max and default values (example). Values with decimal points are used when (max-min)<=5 and min, max or default are non-integer.
Dialog.addCheckbox(label, default) - Adds a checkbox to the dialog, using the specified label and default state (true or false).
Dialog.addCheckboxGroup(rows, columns, labels, defaults) - Adds a rowsxcolumns grid of checkboxes to the dialog, using the specified labels and default states (example).
Dialog.addRadioButtonGroup(label, items, rows, columns, default) - Adds a group of radio buttons to the dialog, where 'label' is the group label, 'items' is an array containing the button labels, 'rows' and 'columns' specify the grid size, and 'default' is the label of the default button. (example).
Dialog.addChoice(label, items) - Adds a popup menu to the dialog, where items is a string array containing the menu items.
Dialog.addChoice(label, items, default) - Adds a popup menu, where items is a string array containing the choices and default is the default choice.
Dialog.addDirectory(label, defaultPath) - Adds a directory field and "Browse" button. The field width is determined by the length of 'defaultPath', with a minimum of 25 and a maximum of 60 columns. Use Dialog getString to retrieve the directory path. Use File.setDefaultDir() to set the default directory used when the user clicks on "Browse". Requires 1.53d.
Dialog.addDirectory(label, defaultPath, columns) - Adds a directory field and "Browse" button, using a field width of 'columns'. Requires 1.54i.
Dialog.addFile(label, defaultPath) - Adds a file field and "Browse" button. The field width is determined by the length of 'defaultPath', with a minimum of 25 and a maximum of 60 columns. Use Dialog getString to retrieve the file path. Requires 1.53d.
Dialog.addFile(label, defaultPath, columns) - Adds a file field and "Browse" button, using a field width of 'columns'. Requires 1.54i.
Dialog.addImage(pathOrURL) - Adds an image to the dialog. The 'pathOrURL' argument can be a file path (e.g., "/Users/wayne/Downloads/blobs.tif") or a URL (e.g., "https://imagej.net/images/blobs.gif").
Dialog.addImageChoice(label) - Adds a popup menu that lists the currently open images. Use Dialog getImageChoice() to retrieve the title of the selected image. The macro aborts if there are no open images. Requires 1.53d.
Dialog.addImageChoice(label, defaultImage) - This a version of addImageChoice() with a second argument for specifying the selected image in the dropdown menu. Requires 1.53s.
Dialog.addHelp(url) - Adds a "Help" button that opens the specified URL in the default browser. This can be used to supply a help page for this dialog or macro. With v1.46b or later, displays an HTML formatted message if 'url' starts with "<html>" (example).
Dialog.addToSameRow() - Makes the next item added appear on the same row as the previous item. May be used for addNumericField, addSlider, addChoice, addCheckbox, addString, addMessage, and before the showDialog() method. In the latter case, the buttons appear to the right of the previous item. Note that addMessage (and addString if a width of more than 8 is specified) use the remaining width, so it must be the last item of a row. Requires 1.51r.
Dialog.setInsets(top, left, bottom) - Overrides the default insets (margins) used for the next component added to the dialog.
Default insets:
   addMessage: 0,20,0 (empty string) or 10,20,0
   addCheckbox: 15,20,0 (first checkbox) or 0,20,0
   addCheckboxGroup: 10,0,0
   addNumericField: 5,0,3 (first field) or 0,0,3
   addStringField: 5,0,5 (first field) or 0,0,5
   addChoice: 5,0,5 (first field) or 0,0,5
Dialog.setLocation(x, y) - Sets the screen location where this dialog will be displayed.
Dialog.getLocation(x, y) - Returns the screen location of this dialog. Requires 1.54g.
Dialog.show() - Displays the dialog and waits until the user clicks "OK" or "Cancel". The macro terminates if the user clicks "Cancel".
Dialog.getString() - Returns a string containing the contents of the next text, directory or file field.
Dialog.getNumber() - Returns the contents of the next numeric field.
Dialog.getCheckbox() - Returns the state (true or false) of the next checkbox.
Dialog.getChoice() - Returns the selected item (a string) from the next popup menu.
Dialog.getRadioButton() - Returns the selected item (a string) from the next radio button group.
Dialog.getImageChoice() - Returns the title of the image selected in the next image choice popup menu.
doCommand("Command")
Runs an ImageJ menu command in a separate thread and returns immediately. As an example, doCommand("Start Animation") starts animating the current stack in a separate thread and the macro continues to execute. Use run("Start Animation") and the macro hangs until the user stops the animation.

doWand(x, y)
Equivalent to clicking on the current image at (x, y) with the wand tool. Note that some objects, especially one pixel wide lines, may not be reliably traced unless they have been thresholded (highlighted in red) using setThreshold.

doWand(x, y, tolerance, mode)
Traces the boundary of the area with pixel values within 'tolerance' of the value of the pixel at (x, y). 'mode' can be "4-connected", "8-connected" or "Legacy". "Legacy" is for compatibility with previous versions of ImageJ; it is ignored if 'tolerance' > 0. If 'mode' contains 'smooth', the contour is smoothed by interpolation (example).

drawLine(x1, y1, x2, y2)
Draws a line between (x1, y1) and (x2, y2). Use setColor() to specify the color of the line and setLineWidth() to vary the line width. See also: Overlay.drawLine.

drawOval(x, y, width, height)
Draws the outline of an oval using the current color and line width. See also: fillOval, setColor, setLineWidth, autoUpdate and Overlay.drawEllipse.

drawRect(x, y, width, height)
Draws the outline of a rectangle using the current color and line width. See also: fillRect, setColor, setLineWidth, autoUpdate and Overlay.drawRect

drawString("text", x, y)
Draws text at the specified location. The first character is drawn obove and to the right of (x, y). Call setFont() to specify the font. Call setJustification() to have the text centered or right justified. Call getStringWidth() to get the width of the text in pixels. Refer to the TextDemo macro for examples and to DrawTextWithBackground to see how to draw text with a background.

drawString("text", x, y, background)
Draws text at the specified location with a filled background (examples).

dump()
Writes the contents of the symbol table, the tokenized macro code and the variable stack to the "Log" window.

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endsWith(string, suffix)
Returns true (1) if string ends with suffix. See also: startsWith, indexOf, substring, matches.

eval(macro)
Evaluates (runs) one or more lines of macro code. An optional second argument can be used to pass a string to the macro being evaluated. See also: EvalDemo macro and runMacro function.

eval("script", javascript)
Evaluates the JavaScript code contained in the string javascript and returns, as a string, the value of the last statement executed. For example eval("script", "IJ.getInstance().setAlwaysOnTop(true);"). See also: runMacro(path, arg).

eval("js", script)
Evaluates the JavaScript code contained in the string script and returns, as a string, the value of the last statement executed. For example eval("js", "Prefs.blackBackground") returns either "true" or "false".

eval("bsh", script)
Evaluates the BeanShell code contained in the string script.

eval("python", script)
Evaluates the Python code contained in the string script.

exec(string or strings)
Executes a native command and returns the output of that command as a string. Also opens Web pages in the default browser and documents in other applications (e.g., Excel). With commands with multiple arguments, each argument should be passed as a separate string. For example
   exec("open", "/Users/wayne/test.jpg", "-a", "/Applications/Gimp.app");
Refer to the ExecExamples macro for examples.

exit
Terminates execution of the macro.

exit("error message")
Terminates execution of the macro and displays an error message.

exp(n)
Returns the exponential number e (i.e., 2.718...) raised to the power of n.

Ext (Macro Extension) Functions
These are functions that have been added to the macro language by plugins using the MacroExtension interface. The Image5D_Extensions plugin, for example, adds functions that work with Image5D. The Serial Macro Extensions plugin adds functions, such as Ext.open("COM8", 9600, "") and Ext.write("a"), that talk to serial devices.

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File Functions
These functions allow you to get information about a file, read or write a text file, create a directory, or to delete, rename or move a file or directory. Note that these functions return a string, with the exception of File.length, File.exists, File.isDirectory, File.rename and File.delete when used in an assignment statement, for example "length=File.length(path)". The FileDemo macro demonstrates how to use these functions. See also: getDirectory and getFileList.

File.append(string, path) - Appends string to the end of the specified file.
File.close(f) - Closes the specified file, which must have been opened using File.open().
File.copy(path1, path2) - Copies a file.
File.dateLastModified(path) - Returns the date and time the specified file was last modified.
File.delete(path) - Deletes the specified file or directory. With v1.41e or later, returns "1" (true) if the file or directory was successfully deleted. If the file is a directory, it must be empty. The file must be in the user's home directory, the ImageJ directory or the temp directory.
File.directory - The directory path of the last file opened using a file open dialog, a file save dialog, drag and drop, open(path) or runMacro(path).
File.exists(path) - Returns "1" (true) if the specified file exists.
File.getName(path) - Returns the file name (e.g., "blobs.tif") from path.
File.getNameWithoutExtension(path) - Returns the name (e.g., "blobs") from path without the extension.
File.getDirectory(path) - Returns the directory (e.g., "C:/Users/wayne/images/") from path.
File.getDefaultDir - Returns the default directory used by file open dialogs or the current working directory if called from a command line macro and File.setDefaultDir() has not been called.
File.setDefaultDir(directoryPath) - Sets the default directory used by file open dialogs.
File.getParent(path) - Returns the parent of the file specified by path.
File.isFile(path) - Returns "1" (true) if the specified file is not a directory.
File.isDirectory(path) - Returns "1" (true) if the specified file is a directory.
File.lastModified(path) - Returns the time the specified file was last modified as the number of milliseconds since January 1, 1970.
File.length(path) - Returns the length in bytes of the specified file as a string, or as a number when used in an assignment statement, for example "length=File.length(path)".
File.makeDirectory(path) - Creates a directory.
File.name - The name of the last file opened using a file open dialog, a file save dialog, drag and drop, or the open(path) function.
File.nameWithoutExtension - The name of the last file opened with the extension removed.
File.open(path) - Creates a new text file and returns a file variable that refers to it. To write to the file, pass the file variable to the print function. Displays a file save dialog box if path is an empty string. The file is closed when the macro exits. Currently, only one file can be open at a time. For an example, refer to the SaveTextFileDemo macro.
File.openAsString(path) - Opens a text file and returns the contents as a string. Displays a file open dialog box if path is an empty string. Use lines=split(str, "\n") to convert the string to an array of lines. See also: File.openUrlAsString.
File.openAsRawString(path) - Opens a file and returns up to the first 5,000 bytes as a string. Returns all the bytes in the file if the name ends with ".txt". Refer to the First10Bytes and ZapGremlins macros for examples.
File.openAsRawString(path, count) - Opens a file and returns up to the first count bytes as a string.
File.openUrlAsString(url) - Opens a URL and returns the contents as a string. Returns an emptly string if the host or file cannot be found. With v1.41i and later, returns "<Error: message>" if there any error, including host or file not found.
File.openSequence(path, options) - Opens the images in the specified directory as a stack. Uses a virtual stack if the 'options' string contains 'virtual'. A filter, image type, start, step, count and scale can also be set, for example "filter=abc bitdepth=32 start=10 step=2 count=10 scale=50". Requires 1.53p.
File.openDialog(title) - Displays a file open dialog and returns the path to the file chosen by the user (example). The macro exits if the user cancels the dialog.
File.rename(path1, path2) - Renames, or moves, a file or directory. Returns "1" (true) if successful.
File.saveString(string, path) - Saves string as a file.
File.separator - Returns the file name separator character ("/" or "\").

fill()
Fills the image or selection with the current drawing color.

fillOval(x, y, width, height)
Fills an oval bounded by the specified rectangle with the current drawing color. See also: drawOval, setColor, autoUpdate.

fillRect(x, y, width, height)
Fills the specified rectangle with the current drawing color. See also: drawRect, setColor, autoUpdate.

Fit Functions
These functions do curve fitting. The CurveFittingDemo macro demonstrates how to use them. Fit.doFit(equation, xpoints, ypoints) - Fits the specified equation to the points defined by xpoints, ypoints. Equation can be either the equation name or an index. The equation names are shown in the drop down menu in the Analyze>Tools>Curve Fitting window. With ImageJ 1.42f or later, equation can be a string containing a user-defined equation (example).
Fit.doFit(equation, xpoints, ypoints, initialGuesses) - Fits the specified equation to the points defined by xpoints, ypoints, using initial parameter values contained in initialGuesses, an array equal in length to the number of parameters in equation (example).
Fit.doWeightedFit(equation, xpoints, ypoints, weights, initialGuesses) - Fits the specified equation to the points defined by 'xpoints', 'ypoints', with the weight of each data point given by the 'weights' array. If the error bars of the individual data points are known, the weights should be proportional to 1/error2. The sum of squared residuals is calculated by multiplying each individual (y - fit)2 value with the corresponding weight. The 'initialGuesses' array is optional.
Fit.rSquared - Returns R^2=1-SSE/SSD, where SSE is the sum of the squares of the errors and SSD is the sum of the squares of the deviations about the mean.
Fit.p(index) - Returns the value of the specified parameter.
Fit.nParams - Returns the number of parameters.
Fit.f(x) - Returns the y value at x (example).
Fit.nEquations - Returns the number of equations.
Fit.getEquation(index, name, formula) - Returns the name and formula of the specified equation.
Fit.getEquation(index, name, formula, macroCode) - Returns the name, formula and macro code of the specified equation.
Fit.plot - Plots the current curve fit.
Fit.logResults - Causes doFit() to write a description of the curve fitting results to the Log window.
Fit.showDialog - Causes doFit() to display the simplex settings dialog.
floodFill(x, y)
Fills, with the foreground color, pixels that are connected to, and the same color as, the pixel at (x, y). Does 8-connected filling if there is an optional string argument containing "8", for example floodFill(x, y, "8-connected"). This function is used to implement the flood fill (paint bucket) macro tool.

floor(n)
Returns the largest value that is not greater than n and is equal to an integer. See also: Math.ceil and round.

fromCharCode(value1, ..., valueN)
This function takes one or more Unicode values and returns a string.

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getArgument()
Returns the string argument passed to macros called by runMacro(macro, arg), eval(macro), IJ.runMacro(macro, arg) or IJ.runMacroFile(path, arg).

getBoolean("message")
Displays a dialog box containing the specified message and "Yes", "No" and "Cancel" buttons. Returns true (1) if the user clicks "Yes", returns false (0) if the user clicks "No" and exits the macro if the user clicks "Cancel".

getBoolean(message, yesLabel, noLabel)
Displays a dialog box containing the specified message and buttons with custom labels.

getBoundingRect(x, y, width, height)
Replace by getSelectionBounds.

getCursorLoc(x, y, z, modifiers)
Returns the cursor location in pixels and the mouse event modifier flags. The z coordinate is zero for 2D images. For stacks, it is one less than the slice number. Use toScaled(x, y) to scale the coordinates. For examples, see the GetCursorLocDemo and the GetCursorLocDemoTool macros.

getDateAndTime(year, month, dayOfWeek, dayOfMonth, hour, minute, second, msec)
Returns the current date and time. Note that 'month' and 'dayOfWeek' are zero-based indexes. For an example, refer to the GetDateAndTime macro. See also: getTime.

getDimensions(width, height, channels, slices, frames)
Returns the dimensions of the current image.

getDirectory(string)
Displays a "choose directory" dialog and returns the selected directory, or returns the path to a specified directory, such as "plugins", "home", etc. The returned path ends with the file separator (either "/" or "\" depending on the OS). Returns an empty string if the specified directory is not found or aborts the macro if the user cancels the "choose directory" dialog box. For examples, see the GetDirectoryDemo and ListFilesRecursively macros. See also: getFileList and the File functions.

getDir(string)
An alias of getDirectory since 1.49q.
Displays a "choose directory" dialog and returns the selected directory, or returns the path to a specified directory, such as "plugins", "home", etc. The returned path ends with the file separator (either "/" or "\" depending on the OS). Returns an empty string if the specified directory is not found or aborts the macro if the user cancels the "choose directory" dialog box. For examples, see the GetDirectoryDemo and ListFilesRecursively macros. See also: getFileList and the File functions. getDir("Choose a Directory") - Displays a file open dialog, using the argument as a title, and returns the path to the directory selected by the user.
getDir("downloads") - Returns the path to the Downloads directory.
getDir("file") - Returns the path most recently used to open or save a file.
getDir("home") - Returns the path to the Home directory.
getDir("image") - Returns the path to the directory that the active image was loaded from.
getDir("imagej") - Returns the path to the ImageJ directory.
getDir("luts") - Returns the path to the luts directory.
getDir("macros") - Returns the path to the macros directory.
getDir("plugins") - Returns the path to the plugins directory.
getDir("startup") - Returns the path to the directory that ImageJ was launched from.
getDir("temp") - Returns the path to the temporary directory (/tmp on Linux and Mac OS X).
getDir("cwd") - Returns the path to the current working directory.
getDir("preferences") - Returns the path to the directory containing "IJ_Prefs.txt".
getDisplayedArea(x, y, width, height)
Returns the pixel coordinates of the actual displayed area of the image canvas. For an example, see the Pixel Sampler Tool.

getFileList(directory)
Returns an array containing the names of the files in the specified directory path. The names of subdirectories have a "/" appended. For an example, see the ListFilesRecursively macro.

getFontList()
Returns an array containing the names of available system fonts (example).

getHeight()
Returns the height in pixels of the current image.

getHistogram(values, counts, nBins[, histMin, histMax])
Returns the histogram of the current image or selection. Values is an array that will contain the pixel values for each of the histogram counts (or the bin starts for 16 and 32 bit images), or set this argument to 0. Counts is an array that will contain the histogram counts. nBins is the number of bins that will be used. It must be 256 for 8 bit and RGB image, or an integer greater than zero for 16 and 32 bit images. With 16-bit images, the Values argument is ignored if nBins is 65536. With 16-bit and 32-bit images, the histogram range can be specified using optional histMin and histMax arguments. See also: getStatistics, HistogramLister, HistogramPlotter, StackHistogramLister and CustomHistogram.

getImageID()
Returns the unique ID (a negative number) of the active image. Use the selectImage(id), isOpen(id) and isActive(id) functions to activate an image or to determine if it is open or active.

getImageInfo()
Returns a string containing the text that would be displayed by the Image>Show Info command. To retrieve the contents of a text window, use getInfo("window.contents"). For an example, see the ListDicomTags macros. See also: getMetadata and Property.getInfo.

getInfo("command.name")
Returns the name of the most recently invoked command. The names of commands invoked using keyboard shortcuts are preceded by "^" (example).

getInfo(DICOM_TAG)
Returns the value of a DICOM tag in the form "xxxx,xxxx", e.g. getInfo("0008, 0060"). Returns an empty string if the current image is not a DICOM or if the tag was not found.

getInfo("font.name")
Returns the name of the current font.

getInfo("image.description")
Returns the TIFF image description tag, or an empty string if this is not a TIFF image or the image description is not available.

getInfo("image.directory")
Returns the directory that the current image was loaded from, or an empty string if the directory is not available.

getInfo("image.filename")
Returns the name of the file that the current image was loaded from, or an empty string if the file name is not available.

getInfo("image.title")
Returns the title of the current image. Same as getTitle.

getInfo("image.subtitle")
Returns the subtitle of the current image. This is the line of information displayed above the image and below the title bar.

getInfo("log")
Returns the contents of the Log window, or "" if the Log window is not open.

getInfo("macro.filepath")
Returns the filepath of the most recently loaded macro or script. Use File.getName(getInfo("macro.filepath")) to get the file name and File.getDirectory(getInfo("macro.filepath")) to get the directory.

getInfo("micrometer.abbreviation")
Returns "µm", the abbreviation for micrometer.

getInfo("os.name")
Returns the OS name ("Mac OS X", "Linux" or "Windows").

getInfo("overlay")
Returns information about the current image's overlay.

getInfo("selection.name")
Returns the name of the current selection, or "" if there is no selection or the selection does not have a name. The argument can also be "roi.name". See also: Roi.getName.

getInfo("selection.color")
Returns the color of the current selection. See also: Roi.getStrokeColor.

getInfo("slice.label")
Return the label of the current stack slice. This is the string that appears in parentheses in the subtitle, the line of information above the image. Returns an empty string if the current image is not a stack or the current slice does not have a label.

getInfo("threshold.method")
Returns the current thresholding method ("IsoData", "Otsu", etc).

getInfo("threshold.mode")
Returns the current thresholding mode ("Red", "B&W" or"Over/Under").

getInfo("window.contents")
If the front window is a text window, returns the contents of that window. If the front window is an image, returns a string containing the text that would be displayed by Image>Show Info. Note that getImageInfo() is a more reliable way to retrieve information about an image. Use split(getInfo(), '\n') to break the string returned by this function into separate lines. Replaces the getInfo() function.

getInfo("window.title")
Returns the title of the front-most window. Use getTitle to get the title of the current batch mode image.

getInfo("window.type")
Returns the type ("Image", "Text", "ResultsTable", "Editor", "Plot", "Histogram", etc.) of the front window.

getInfo(key)
Returns the Java property associated with the specified key (e.g., "java.version", "os.name", "user.home", "user.dir", etc.). Returns an empty string if there is no value associated with the key. See also: getList("java.properties").

getLine(x1, y1, x2, y2, lineWidth)
Returns the starting coordinates, ending coordinates and width of the current straight line selection. The coordinates and line width are in pixels. Sets x1 = -1 if there is no line selection. Refer to the GetLineDemo macro for an example. See also: makeLine.

getList("image.titles")
Returns a list (array) of image window titles. For an example, see the DisplayWindowTitles macro.

getList("window.titles")
Returns a list (array) of non-image window titles. For an example, see the DisplayWindowTitles macro.

getList("java.properties")
Returns a list (array) of Java property keys. For an example, see the DisplayJavaProperties macro. See also: getInfo(key).

getList("threshold.methods")
Returns a list of the available automatic thresholding methods (example).

getList("LUTs")
Returns, as an array, a list of the LUTs in the Image>Lookup Tables menu (example).

getLocationAndSize(x, y, width, height)
Returns the location and size, in screen coordinates, of the active image window. Use getWidth and getHeight to get the width and height, in image coordinates, of the active image. See also: setLocation,

getLut(reds, greens, blues)
Returns three arrays containing the red, green and blue intensity values from the current lookup table. See the LookupTables macros for examples.

getMetadata("Info")
Returns the metadata (a string) from the "Info" property of the current image. With DICOM images, this is the information (tags) in the DICOM header. See also: setMetadata and Property.getInfo.

getMetadata("Label")
Returns the current slice label. The first line of the this label (up to 60 characters) is displayed as part of the image subtitle. With DICOM stacks, returns the metadata (tags) from the DICOM header. See also: Property.getSliceLabel and Property.setSliceLabel.

getMinAndMax(min, max)
Returns the minimum and maximum displayed pixel values (display range). See the DisplayRangeMacros for examples.

getNumber("prompt", defaultValue)
Displays a dialog box and returns the number entered by the user. The first argument is the prompting message and the second is the value initially displayed in the dialog. Exits the macro if the user clicks on "Cancel" in the dialog. Returns defaultValue if the user enters an invalid number. See also: Dialog.create.

getPixel(x, y)
Returns the raw value of the pixel at (x, y). Uses bilinear interpolation if 'x' or 'y' are not integers. Use getValue(x,y) to get calibrated pixel values from 8 and 16 bit images and intensity values from RGB images. The getPixel() function returns zero for locations outside the image and getValue() returns NaN. The pixels in RGB images contain red, green and blue components that need to be extracted using shifting and masking. See the Color Picker Tool macro for an example that shows how to do this.

getPixelSize(unit, pixelWidth, pixelHeight)
Returns the unit of length (as a string) and the pixel dimensions. For an example, see the ShowImageInfo macro. See also: getVoxelSize.

getProfile()
Runs Analyze>Plot Profile (without displaying the plot) and returns the intensity values as an array. For an example, see the GetProfileExample macro. See also: Plot.getValues().

getRawStatistics(nPixels, mean, min, max, std, histogram)
This function is similar to getStatistics except that the values returned are uncalibrated and the histogram of 16-bit images has a bin width of one and is returned as a max+1 element array. For examples, refer to the ShowStatistics macro set. See also: calibrate and List.setMeasurements

getResult("Column", row)
Returns a measurement from the ImageJ results table or NaN if the specified column is not found. The first argument specifies a column in the table. It must be a "Results" window column label, such as "Area", "Mean" or "Circ.". The second argument specifies the row, where 0<=row<nResults. nResults is a predefined variable that contains the current measurement count. (Actually, it's a built-in function with the "()" optional.) Omit the second argument and the row defaults to nResults-1 (the last row in the results table). See also: nResults, setResult, isNaN, getResultLabel.

getResultString("Column", row)
Returns a string from the ImageJ results table or "null" if the specified column is not found. The first argument specifies a column in the table. The second specifies the row, where 0<=row<nResults.

getResultLabel(row)
Returns the label of the specified row in the results table, or an empty string if Display Label is not checked in Analyze>Set Measurements.

getSelectionBounds(x, y, width, height)
Returns the smallest rectangle that can completely contain the current selection. x and y are the pixel coordinates of the upper left corner of the rectangle. width and height are the width and height of the rectangle in pixels. If there is no selection, returns (0, 0, ImageWidth, ImageHeight). See also: selectionType and setSelectionLocation.

getSelectionCoordinates(xpoints, ypoints)
Returns two arrays containing the X and Y coordinates, in pixels, of the points that define the current selection. See the SelectionCoordinates macro for an example. See also: selectionType, getSelectionBounds.

getSliceNumber()
Returns the number of the currently displayed stack image, an integer between 1 and nSlices. Returns 1 if the active image is not a stack. See also: setSlice, Stack.getPosition.

getStatistics(area, mean, min, max, std, histogram)
Returns the area, average pixel value, minimum pixel value, maximum pixel value, standard deviation of the pixel values and histogram of the active image or selection. The histogram is returned as a 256 element array. For 8-bit and RGB images, the histogram bin width is one. For 16-bit and 32-bit images, the bin width is (max-min)/256. For examples, refer to the ShowStatistics macro set. Note that trailing arguments can be omitted. For example, you can use getStatistics(area), getStatistics(area, mean) or getStatistics(area, mean, min, max). See also: getRawStatistics and List.setMeasurements

getString("prompt", "default")
Displays a dialog box and returns the string entered by the user. The first argument is the prompting message and the second is the initial string value. Exits the macro if the user clicks on "Cancel" or enters an empty string. See also: Dialog.create.

getStringWidth(string)
Returns the width in pixels of the specified string. See also: getValue("font-height"), String.setFontSize, setFont and drawString.

getThreshold(lower, upper)
Returns the lower and upper threshold levels. Both variables are set to -1 if the active image is not thresholded. See also: setThreshold, getThreshold, resetThreshold.

getTime()
Returns the current time in milliseconds. The granularity of the time varies considerably from one platform to the next. On Windows NT, 2K, XP it is about 10ms. On other Windows versions it can be as poor as 50ms. On many Unix platforms, including Mac OS X, it actually is 1ms. See also: getDateAndTime.

getTitle()
Returns the title of the current image.

getValue(x, y)
Returns calibrated pixel values from 8 and 16 bit images and intensity values from RGB images. Uses bilinear interpolation if 'x' or 'y' are not integers. Use getPixel(x, y) to read raw pixel values.

getValue("color.foreground")
Returns the current foreground color as a value that can be passed to the setColor(value) function. The value returned is the pixel value used by the Edit>Fill command and by drawing tools.

getValue("color.background")
Returns the current background color as a value that can be passed to the setColor(value) function. The value returned is the pixel value used by the Edit>Clear command.

getValue("rgb.foreground")
Returns the current foreground color as an RGB pixel value (example).

getValue("rgb.background")
Returns the current background color as an RGB pixel value.

getValue("font.size")
Returns the size, in points, of the current font.

getValue("font.height")
Returns the height, in pixels, of the current font.

getValue("selection.size")
Returns the number of points in the current selection, or 0 if there is no selection. See also: Roi.size.

getValue("selection.width")
Returns the stroke width of the current selection. See also: Roi.getStrokeWidth.

getValue("results.count")
Returns the number of lines in the current results table. Unlike nResults, works with tables that are not named "Results".

getValue("rotation.angle")
Returns the current Image>Transform>Rotate angle.

getValue("image.size")
Returns the size of the current image in bytes.

getValue("Mean, Median, Feret, etc.")
Returns a measurement result, where the argument is "Area", "Mean", "StdDev", "Mode", "Min", "Max", "X", "Y", "XM", "YM", "Perim.", "BX", "BY", "Width", "Height", "Major", "Minor", "Angle", "Circ.", "Feret", "IntDen", "Median", "Skew", "Kurt", "%Area", "RawIntDen", "Ch", "Slice", "Frame", "FeretX", "FeretY", "FeretAngle", "MinFeret", "AR", "Round", "Solidity", "MinThr", "MaxThr" or "Length". Add " raw" to the argument to disable calibration, for example getValue("Mean raw"). Add " limit" to the argument to enable the "limit to threshold" option.

getVoxelSize(width, height, depth, unit)
Returns the voxel size and unit of length ("pixel", "mm", etc.) of the current image or stack. See also: getPixelSize, setVoxelSize.

getVersion()
Returns the ImageJ version number as a string (e.g., "1.34s"). See also: IJ.getFullVersion.

getWidth()
Returns the width in pixels of the current image.

getZoom()
Returns the magnification of the active image, a number in the range 0.03125 to 32.0 (3.1% to 3200%).

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IJ Functions
These functions provide access to miscellaneous methods in ImageJ's IJ class. IJ.deleteRows(index1, index2) - Deletes rows index1 through index2 in the results table.
IJ.getToolName() - Returns the name of the currently selected tool. See also: setTool.
IJ.getFullVersion - Returns the ImageJ version and build number as a string (e.g., "1.52d11").
IJ.freeMemory() - Returns the memory status string (e.g., "2971K of 658MB (<1%)") that is displayed when the users clicks in the ImageJ status bar.
IJ.checksum("MD5 string", string) - Returns the MD5 (or SHA-256) checksum from a string.
IJ.checksum("MD5 file", filepath) - Returns the MD5 (or SHA-256) checksum from a file. If 'filepath' is a directory or invalid, "0" is returned.
IJ.currentMemory() - Returns, as a string, the amount of memory in bytes currently used by ImageJ.
IJ.log(string) - Displays string in the Log window.
IJ.maxMemory() - Returns, as a string, the amount of memory in bytes available to ImageJ. This value (the Java heap size) is set in the Edit>Options>Memory & Threads dialog box.
IJ.pad(n, length) - Pads 'n' with leading zeros and returns the result (example). Note that 'n' can be either a number or a string. See also: String.pad.
IJ.redirectErrorMessages() - Causes next image opening error to be redirected to the Log window and prevents the macro from being aborted (example).
IJ.renameResults(name) - Changes the title of the "Results" table to the string name.
IJ.renameResults(oldName, newName) - Changes the title of a results table from oldName to newName.
Image Functions
Functions for working with the active image, available in ImageJ 1.53f and later. Image.title
The title of the active image. Requires 1.53h.
Image.width
The width of the active image.
Image.height
The height of the active image.
Image.copy
Copies the contents of the current selection, or the entire image if there is no selection, to the internal clipboard.
Image.paste(x, y)
Inserts the contents of the internal clipboard at the specified location in the active image.
Image.paste(x, y, mode)
Inserts the contents of the internal clipboard at x,y using the specified transfer mode ("Copy", "Blend", "Average", "Difference", "Transparent", "Transparent2", "AND", "OR", "XOR", "Add", "Subtract", "Multiply", or "Divide""Copy", "Blend", "Average", "Difference", "Transparent", "Transparent2", "AND", "OR", "XOR", "Add", "Subtract", "Multiply", or "Divide").
imageCalculator(operator, img1, img2)
Runs the Process>Image Calculator tool, where operator ("add", "subtract", "multiply", "divide", "and", "or", "xor", "min", "max", "average", "difference" or "copy") specifies the operation, and img1 and img2 specify the operands. img1 and img2 can be either an image title (a string) or an image ID (an integer). The operator string can include up to three modifiers: "create" (e.g., "add create") causes the result to be stored in a new window, "32-bit" causes the result to be 32-bit floating-point and "stack" causes the entire stack to be processed. See the ImageCalculatorDemo macros for examples.

indexOf(string, substring)
Returns the index within string of the first occurrence of substring. See also: lastIndexOf, startsWith, endsWith, substring, toLowerCase, replace, matches.

indexOf(string, substring, fromIndex)
Returns the index within string of the first occurrence of substring, with the search starting at fromIndex.

is("animated")
Returns true if the current image is an animated stack.

is("applet")
Returns true if ImageJ is running as an applet.

is("area")
Returns true if the current image has an area selection.

is("Batch Mode")
Returns true if the macro interpreter is running in batch mode.

is("binary")
Returns true if the current image is binary (8-bit with only 0 and 255 values).

is("Caps Lock Set")
Returns true if the caps lock key is set. Always return false on some platforms.

is("changes")
Returns true if the current image's 'changes' flag is set.

is("composite")
Returns true if the current image is a a multi-channel stack that uses the CompositeImage class.

is("FFT")
Returns true if the current image is a Fourier transform image, an 8-bit image showing the logarithm of the power spectrum, with the full Fourier transform data in the background (so you can do an inverse transform).

is("global scale")
Returns true if there is global spatial calibration.

is("grayscale")
Returns true if the current image is grayscale, or an RGB image with identical R, G and B channels.

is("Inverting LUT")
Returns true if the current image is using an inverting (monotonically decreasing) lookup table.

is("InvertY")
Returns true if the 'invertY' property of the active image is enabled.

is("line")
Returns true if the current image has a line selection.

is("locked")
Returns true if the current image is locked.

is("Virtual Stack")
Returns true if the current image is a virtual stack.

isActive(id)
Returns true if the image with the specified ID is active.

isKeyDown(key)
Returns true if the specified key is pressed, where key must be "shift", "alt" or "space". See also: setKeyDown.

isNaN(n)
Returns true if the value of the number n is NaN (Not-a-Number). A common way to create a NaN is to divide zero by zero. Comparison with a NaN always returns false so "if (n!=n)" is equivalent to (isNaN(n))". Note that the numeric constant NaN is predefined in the macro language. The NaNs macro demonstrates how to remove NaNs from an image.

isOpen(id)
Returns true if the image with the specified ID is open.

isOpen("Title")
Returns true if the window with the specified title is open.

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lastIndexOf(string, substring)
Returns the index within string of the rightmost occurrence of substring. See also: indexOf, startsWith, endsWith, substring.

lengthOf(str)
Returns the length of a string or array. Can be replaced with str.length (1.52t or later) or arr.length, where is 'str' is a string variable and 'arr' is an array variable.

lineTo(x, y)
Draws a line from current location to (x, y) . See also: Overlay.lineTo.

List Functions
These functions work with a list of key/value pairs. The ListDemo macro demonstrates how to use them. List.set(key, value) - Adds a key/value pair to the list.
List.get(key) - Returns the string value associated with key, or an empty string if the key is not found.
List.getValue(key) - When used in an assignment statement, returns the value associated with key as a number. Aborts the macro if the value is not a number or the key is not found.
List.size - Returns the size of the list.
List.clear() - Resets the list.
List.setList(list) - Loads the key/value pairs in the string list.
List.getList - Returns the list as a string.
List.setMeasurements - Measures the current image or selection and loads the resulting keys (Results table column headings) and values into the list. Use List.setMeasurements("limit") to measure using the "Limit to threshold" option. All parameters listed in the Analyze>Set Measurements dialog box are measured, including those that are unchecked. Use List.getValue() in an assignment statement to retrieve the values. See the DrawEllipse macro for an example. With ImageJ 1.52p or later, it is easier to use the getValue() function to get a single measurement value. Examples: getValue("Mean"), getValue("Mean limit") and getValue("Mean raw").
List.setMeasurements("limit") - This is a version of List.setMeasurements that enables the "Limit to threshold" option.
List.setCommands - Loads the ImageJ menu commands (as keys) and the plugins that implement them (as values).
List.toArrays(keys, values) - Retrieves keys and values as a pair of string arrays, sorted alphabetically for keys.
List.fromArrays(keys, values) - Creates the List from keys and values arrays.
List.indexOf(key) - Returns the alphabetic position of the specified key, or -1 if not found. Note that this function, as well as List.size, returns a string.
log(n)
Returns the natural logarithm (base e) of n. Note that log10(n) = log(n)/log(10). See also: Math.log10.

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makeArrow(x1, y1, x2, y2, style)
Creates an arrow selection, where 'style' is a string containing "filled", "notched", "open", "headless" or "bar", plus the optionial modifiers "outline", "double", "small", "medium" and "large" (example). See also: Roi.setStrokeWidth and Roi.setStrokeColor.

makeEllipse(x1, y1, x2, y2, aspectRatio)
Creates an elliptical selection, where x1,y1,x2,y2 specify the major axis of the ellipse and aspectRatio (<=1.0) is the ratio of the lengths of minor and major axis.

makeLine(x1, y1, x2, y2)
Creates a new straight line selection. The origin (0, 0) is assumed to be the upper left corner of the image. Coordinates are in pixels. You can create segmented line selections by specifying more than two coordinate pairs, for example makeLine(25, 34, 44, 19, 69, 30, 71, 56). After creating the selection, use Roi.setStrokeWidth to set the width and Roi.setStrokeColor to set the color.

makeLine(x1, y1, x2, y2, lineWidth)
Creates a straight line selection with the specified width. See also: getLine.

makeLine(x1, y1, x2, y2, x3, y3, ...)
Creates a segmented line selection. After creating the selection, use Roi.setStrokeWidth to set the width and Roi.setStrokeColor to set the color. See also: makeSelection("polyline", xpoints, ypoints).

makeOval(x, y, width, height)
Creates an elliptical selection, where (x, y) define the upper left corner of the bounding rectangle of the ellipse.

makePoint(x, y, options)
Creates a point selection at the specified location, with the type ('hybrd', 'cross', 'dot' or 'circle'), color ('red', 'white', etc.) and size ('tiny', 'small', 'medium', 'large' or 'extra large') of the point defined in the 'options' string (example). The point is added to an overlay if the options string contains 'add'.

Create a multi-point selection by using makeSelection("point", xpoints, ypoints). All the makePoint() options ('cross', 'small', 'red', etc.) can be added to first argument.

makePoint(x, y)
Creates a point selection at the specified location. Create a multi-point selection by using makeSelection("point", xpoints, ypoints). Use setKeyDown("shift"); makePoint(x, y); to add a point to an existing point selection.

makePolygon(x1, y1, x2, y2, x3, y3, ...)
Creates a polygonal selection, where at least three coordinate pairs must be specified. As an example, makePolygon(20, 48, 59, 13, 101, 40, 75, 77, 38, 70) creates a polygon selection with five sides. See also: makeSelection("polygon", xpoints, ypoints).

makeRectangle(x, y, width, height)
Creates a rectangular selection, where x and y are the coordinates (in pixels) of the upper left corner of the selection. The origin (0, 0) of the coordinate system is the upper left corner of the image.

makeRectangle(x, y, width, height, arcSize)
Creates a rounded rectangular selection using the specified corner arc size.

makeRotatedRectangle(x1, y1, x2, y2, width)
Creates a rotated rectangular selection, which is similar to a wide line where (x1, y1) is the start of the line, (x2, y2) is the end of the line and 'width' is the line width.

makeSelection(type, xpoints, ypoints)
Creates a selection from a list of XY coordinates. The first argument should be "polygon", "freehand", "polyline", "freeline", "angle" or "point", or the numeric value returned by selectionType. The xpoints and ypoints arguments are numeric arrays that contain the X and Y coordinates. See the MakeSelectionDemo macro for examples.

When creating a multi-point selection and using ImageJ 1.52i or later, the first argument can include words that define the type ('hybrd', 'cross', 'dot' or 'circle'), color ('red', 'white', etc.) and size ('tiny', 'small', 'medium', 'large' or 'extra large') of the points (e.g., "point small red cross").

makeText(string, x, y)
Creates a text selection, where x and y are the coordinates (in pixels) of the upper left corner of the selection. The selection will use the font and size specified by the last call to setFont(). The CreateOverlay macro provides an example.

matches(string, regex)
Returns true if string matches the specified regular expression. Can be replaced with string.matches(regex) in ImageJ 1.52t or later. See also: startsWith, endsWith, indexOf, replace.

Math Functions
Functions for performing basic numeric operations, available in ImageJ 1.52u or later. Math.abs(n)
Returns the absolute value of n.
Math.acos(n)
Returns the inverse cosine (in radians) of n.
Math.asin(n)
Returns the inverse sine (in radians) of n.
Math.atan(n)
Returns the inverse tangent (arctangent) of n, a value in the range -PI/2 through PI/2.
Math.atan2(y, x)
Calculates the inverse tangent of y/x and returns an angle in the range -PI to PI, using the signs of the arguments to determine the quadrant. Multiply the result by 180/PI to convert to degrees.
Math.ceil(n)
Returns the smallest (closest to negative infinity) value that is greater than or equal to n and is an integer.
Math.cos(angle)
Returns the cosine of an angle (in radians).
Math.erf(x)
Returns an approximation of the error function.
Math.exp(n)
Returns the exponential number e (i.e., 2.718...) raised to the power of n.
Math.floor(n)
Returns the largest value that is not greater than n and is equal to an integer.
Math.log(n)
Returns the natural logarithm (base e) of n.
Math.log10(n)
Returns the base 10 logarithm of n.
Math.min(n1, n2)
Returns the smaller of two values.
Math.max(n1, n2)
Returns the larger of two values.
Math.pow(base, exponent)
Returns the value of base raised to the power of exponent.
Math.round(n)
Returns the closest integer to n.
Math.sin(angle)
Returns the sine of an angle (in radians).
Math.sqr(n)
Returns the square of n.
Math.sqrt(n)
Returns the square root of n, or NaN if n is less than zero.
Math.tan(n)
Returns the tangent of an angle (in radians).
Math.toRadians(degrees)
Converts an angle in degrees to an equivalent angle in radians. Requires 1.53f.
Math.toDegrees(radians)
Converts an angle in radians to an equivalent angle in degrees. Requires 1.53f.
Math.constrain(n, min, max)
Limits 'n' to the range 'min'-'max'. Requires 1.53n.
Math.map(n, low1, high1, low2, high2)
Maps the value 'n' in the input range 'low1'-'high1' to the output range 'low2'-'high2'. Requires 1.53n.
maxOf(n1, n2)
Returns the greater of two values. See also: Math.max.

minOf(n1, n2)
Returns the smaller of two values. See also: Math.min.

moveTo(x, y)
Sets the current drawing location. The origin is always assumed to be the upper left corner of the image.

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newArray(size)
Returns a new array containing size elements. You can also create arrays by listing the elements, for example newArray(1, 4, 7) or newArray("a", "b", "c"). For more examples, see the Arrays macro.

In ImageJ 1.53g or newer, arrays automatically expand in size as needed (example). To use expandable arrays in earlier versions, call setOption("ExpandableArrays", true).

The ImageJ macro language does not directly support 2D arrays. As a work around, either create a blank image and use setPixel() and getPixel(), or create a 1D array using a=newArray(xmax*ymax) and do your own indexing (e.g., value=a[x+y*xmax]).

newImage(title, type, width, height, depth)
Opens a new image or stack using the name title. The string type should contain "8-bit", "16-bit", "32-bit" or "RGB". In addition, it can contain "white", "black" or "ramp" (the default is "white"). As an example, use "16-bit ramp" to create a 16-bit image containing a grayscale ramp. Precede with call("ij.gui.ImageWindow.setNextLocation", x, y) to set the location of the new image. Width and height specify the width and height of the image in pixels. Depth specifies the number of stack slices.

newMenu(macroName, stringArray)
Defines a menu that will be added to the toolbar when the menu tool named macroName is installed. Menu tools are macros with names ending in "Menu Tool". StringArray is an array containing the menu commands. Returns a copy of stringArray. For an example, refer to the Toolbar Menus toolset.

nImages
Returns number of open images. The parentheses "()" are optional.

nResults
Returns the current measurement counter value. The parentheses "()" are optional. See also: getValue("results.count").

nSlices
Returns the number of images in the current stack. Returns 1 if the current image is not a stack. The parentheses "()" are optional. See also: getSliceNumber, getDimensions.

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open(path)
Opens and displays a tiff, dicom, fits, pgm, jpeg, bmp, gif, lut, roi, or text file. Displays an error message and aborts the macro if the specified file is not in one of the supported formats, or if the file is not found. Displays a file open dialog box if path is an empty string or if there is no argument. Use the File>Open command with the command recorder running to generate calls to this function. With 1.41k or later, opens images specified by a URL, for example open("../../images/clown.gif"). With 1.49v or later, opens a folder of images as a stack. Use open("path/to/folder", "virtual") to open a folder of images as a virtual stack.

open(path, n)
Opens the nth image in the TIFF stack specified by path. For example, the first image in the stack is opened if n=1 and the tenth is opened if n=10.

Overlay Functions
Use these functions to create and manage non-destructive graphic overlays. For an exmple, refer to the OverlayPolygons macro. See also: setColor, setLineWidth and setFont. Overlay.moveTo(x, y)
Sets the current drawing location.
Overlay.lineTo(x, y)
Draws a line from the current location to (x, y) .
Overlay.drawLine(x1, y1, x2, y2)
Draws a line between (x1, y1) and (x2, y2).
Overlay.add
Adds the drawing created by Overlay.lineTo(), Overlay.drawLine(), etc. to the overlay without updating the display.
Overlay.setPosition(n)
Sets the stack position (slice number) of the last item added to the overlay (example). Set the position to 0 and the item will be displayed on all stack slices.
Overlay.setPosition(c, z, t)
Sets the hyperstack position (channel, slice, frame) of the last item added to the overlay. Set a position to 0 and the item will be displayed on all the corresponding channels, slices or frames.
Overlay.drawRect(x, y, width, height)
Draws a rectangle, where (x, y) specifies the upper left corner.
Overlay.drawEllipse(x, y, width, height)
Draws an ellipse, where (x, y) specifies the upper left corner of the bounding rectangle.
Overlay.drawString("text", x, y)
Draws text at the specified location and adds it to the overlay. The first character is drawn obove and to the right of (x, y). Use setFont() to specify the font and setColor to set specify the color (example).
Overlay.drawString("text", x, y, angle)
Draws text at the specified location and angle and adds it to the overlay (example).
Overlay.show
Displays the current overlay.
Overlay.hide
Hides the current overlay.
Overlay.hidden
Returns true if the active image has an overlay and it is hidden.
Overlay.remove
Removes the current overlay.
Overlay.clear
Resets the overlay without updating the display.
Overlay.size
Returns the size (selection count) of the current overlay. Returns zero if the image does not have an overlay.
Overlay.addSelection
Adds the current selection to the overlay.
Overlay.addSelection(strokeColor)
Sets the stroke color ("red", "green", "ff8800", etc.) of the current selection and adds it to the overlay.
Overlay.addSelection(strokeColor, strokeWidth)
Sets the stroke color ("blue", "yellow", "ffaa77" etc.) and stroke width of the current selection and adds it to the overlay.
Overlay.addSelection("", 0, fillColor)
Sets the fill color ("red", "green", etc.) of the current selection and adds it to the overlay.
Overlay.activateSelection(index)
Activates the specified overlay selection.
Overlay.activateSelectionAndWait(index)
Activates the specified overlay selection and waits for the display to finish updating.
Overlay.removeSelection(index)
Removes the specified selection from the overlay.
Overlay.update(index)
Replaces the overlay selection at 'index' with the current selection. Analogous to roiManager("update").
Overlay.moveSelection(index, x, y)
Moves the specified selection to the specified location.
Overlay.indexAt(x, y)
Returns the index of the last selection in the overlay containing the point (x, y), or an empty string if no selection contains the point. Requires 1.53b.
Overlay.getBounds(index, x, y, width, height)
Returns the bounding rectangle of the selection in the overlay specified by 'index'. Requires 1.53b.
Overlay.removeRois(name)
Removes the selections named 'name' from the overlay. Requires 1.53b.
Overlay.copy
Copies the overlay on the current image to the overlay clipboard.
Overlay.paste
Copies the overlay on the overlay clipboard to the current image.
Overlay.drawLabels(boolean)
Enables/disables overlay labels.
Overlay.setLabelFontSize(size, options)
Sets the label font size. The options string can contain 'scale' (enlarge labels when image zoomed), 'bold' (display bold labels) or 'back' (display labels with contrasting background color.
Overlay.setLabelColor(color)
Sets the color used to draw labels.
Overlay.useNamesAsLabels(boolean)
Controls whether ROI names or index numbers are used as labels.
Overlay.selectable(false)
Prevents the selections in this overlay from being activated by clicking on their labels or by long clicking. Requires 1.51r.
Overlay.measure
Measures all the selections in the current overlay.
Overlay.setStrokeColor(color)
Sets the stroke color all the selections in the current overlay.
Overlay.setStrokeWidth(width)
Sets the stroke width all the selections in the current overlay.
Overlay.flatten
Creates a new RGB image that has the overlay rendered as pixel data.
Overlay.cropAndSave(dir, format)
Saves the contents of the overlay selections as separate images, where 'dir' is the directory path and 'format' is "tif", "png" or "jpg". Set 'format' to "show" and the images will be displayed in a stack and not saved. Requires 1.53d.
Overlay.fill(color)
Fills all the selections in the overlay with 'color'. Requires 1.53h.
Overlay.fill(color1, color2)
Fills all the selections in the overlay with 'color1' after clearing the image to 'color2'. Requires 1.53h.
Overlay.xor(array)
Creates a selection that is the result of XORing all the selections in the overlay that have an index in 'array'. Requires 1.53h.
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parseFloat(string)
Converts the string argument to a number and returns it. Returns NaN (Not a Number) if the string cannot be converted into a number. Use the isNaN() function to test for NaN. For examples, see ParseFloatIntExamples.

parseFloat("Infinity")
Returns the special floating point value representing +Infinity.

parseFloat("-Infinity")
Returns the special floating point value representing -Infinity.

parseFloat("NaN")
Returns the special floating point value representing NaN (not a number).

parseInt(string)
Converts string to an integer and returns it. Returns NaN if the string cannot be converted into a integer.

parseInt(string, radix)
Converts string to an integer and returns it. The optional second argument (radix) specifies the base of the number contained in the string. The radix must be an integer between 2 and 36. For radixes above 10, the letters of the alphabet indicate numerals greater than 9. Set radix to 16 to parse hexadecimal numbers. Returns NaN if the string cannot be converted into a integer. For examples, see ParseFloatIntExamples.

PI
Returns the constant π (3.14159265), the ratio of the circumference to the diameter of a circle.

Plot Functions
Use these functions to generate and display plots. For examples, check out the Example Plot, More Example Plots, AdvancedPlots, Semi-log Plot and Arrow Plot macros. Plot.create("Title", "X-axis Label", "Y-axis Label", xValues, yValues)
Generates a plot using the specified title, axis labels and X and Y coordinate arrays. If only one array is specified it is assumed to contain the Y values and a 0..n-1 sequence is used as the X values. It is also permissible to specify no arrays and use Plot.setLimits() and Plot.add() to generate the plot. Use Plot.show() to display the plot in a window, or it will be displayed automatically when the macro exits.
Plot.create("Title", "{cat1, cat2, cat3}", "Y-axis Label")
Draws category labels instead of x-axis numbers 0, 1, 2.
Plot.add(type, xValues, yValues)
Adds a curve, set of points or error bars to a plot created using Plot.create(). If only one array is specified it is assumed to contain the Y values and a 0..n-1 sequence is used as the X values. The first argument (type) can be "line", "connected circle", "filled", "bar", "separated bar", "circle", "box", "triangle", "diamond", "cross", "x", "dot", "error bars" (in y direction) or "xerror bars". Run Help>Examples>Plots>Plot Styles to see examples. Error bars (supplied by an optional fourth argument) apply to the last dataset provided by Plot.create or Plot.add.
Plot.add(type, xValues, yValues, label)
Adds a curve or set of points to the plot and sets the dataset label used by Plot.showValuesWithLabels.
Plot.addHistogram(values, binWidth, binCenter)
Creates a 'staircase' histogram from array 'values'. If 'binWidth' is 0, automatic binning is applied. 'binCenter' is optional with default=0. BinCenter can, for example, be set to an expected symmetry point for avoiding artificial asymmetry.
Plot.drawVectors(xStarts, yStarts, xEnds, yEnds)
Draws arrows from the starting to ending coordinates contained in the arrays.
Plot.drawLine(x1, y1, x2, y2)
Draws a line between x1,y1 and x2,y2, using the coordinate system defined by Plot.setLimits().
Plot.drawNormalizedLine(x1, y1, x2, y2)
Draws a line using a normalized 0-1, 0-1 coordinate system, with (0, 0) at the top left and (1, 1) at the lower right corner.
Plot.addText("A line of text", x, y)
Adds text to the plot at the specified location, where (0, 0) is the upper left corner of the the plot frame and (1, 1) is the lower right corner. Call Plot.setJustification() to have the text centered or right justified. Plot.setLimits(xMin, xMax, yMin, yMax)
Sets the range of the x-axis and y-axis of plots. With version 1.50g and later, when 'NaN' is used as a limit, the range is calculated automatically from the plots that have been added so far.
Plot.getLimits(xMin, xMax, yMin, yMax)
Returns the current axis limits. Note that min>max if the axis is reversed.
Plot.setLimitsToFit()
Sets the range of the x and y axes to fit all data.
Plot.setColor(color)
Specifies the color used in subsequent calls to Plot.add() or Plot.addText(). The argument can be "black", "blue", "cyan", "darkGray", "gray", "green", "lightGray", "magenta", "orange", "pink", "red", "white", "yellow", or a hex value like "#ff00ff". Note that the curve specified in Plot.create() is drawn last.
Plot.setColor(color1, color2)
This is a two argument version of Plot.setColor, where the second argument is used for filling symbols or as the line color for connected points.
Plot.setBackgroundColor(color)
Sets the background color of the plot frame (example).
Plot.setLineWidth(width)
Specifies the width of the line used to draw a curve. Symbols (circle, box, etc.) are also drawn larger if a line width greater than one is specified. Note that the curve specified in Plot.create() is the last one drawn before the plot is displayed or updated.
Plot.setJustification("center")
Specifies the justification used by Plot.addText(). The argument can be "left", "right" or "center". The default is "left".
Plot.setLegend("label1\tlabel2...", "options")
Creates a legend for each of the data sets added with Plot.create and Plot.add. In the first argument, the labels for the data sets should be separated with tab or newline characters. The optional second argument can contain the legend position ("top-left", "top-right", "bottom-left", "bottom-right"; default is automatic positioning), "bottom-to-top" for reversed sequence of the labels, and "transparent" to make the legend background transparent.
Plot.setFrameSize(width, height)
Sets the plot frame size in pixels, overriding the default size defined in the Edit>Options>Profile Plot Options dialog box.
Plot.getFrameBounds(x, y, width, height)
Returns the plot frame bounds.
Plot.setLogScaleX(boolean)
Sets the x axis scale to Logarithmic, or back to linear if the optional boolean argument is false. In versions up to 1.49s, it must be called immediately after Plot.create and before Plot.setLimits. See the LogLogPlot macro for an example.
Plot.setLogScaleY(boolean)
Sets the y axis scale to Logarithmic, or back to linear if the optional boolean argument is false.
Plot.setXYLabels("x Label", "y Label")
Sets the axis labels.
Plot.setFontSize(size, "options")
Sets the default font size in the plot (otherwise specified in Profile Plot Options), used e.g. for axes labels. Can be also called prior to Plot.addText. The optional second argument can include "bold" and/or "italic".
Plot.setAxisLabelSize(size, "options")
Sets the fort size of the axis labels. The optional second argument can include "bold" and/or "italic".
Plot.setFormatFlags("11001100001111")
Controls whether to draw axes labels, grid lines and ticks (major/minor/ticks for log axes). Use the macro recorder and More>>Axis Options in any plot window to determine the binary code.
Plot.setStyle(index, styleString)
Set the style of the plot object (curve, label, etc.) with the specified index, using a comma-delimiterd string ("color1, color2, line width, symbol"). For an example, run the Help>Examples>Plots>Plot Styles command.
Plot.freeze(boolean)
Freezes or unfreezes the plot. In the frozen state, the plot cannot be resized or updated. In the unfrozen state, the plot cannot be tiled.
Plot.setOptions(string)
Sets options for the plot. Multiple options may be separated by whitespace or commas. Note that whitespace surrounding the '=' characters is not allowed. Currently recognized options are:
"addhspace=10 addvspace=5" - Increases the left and right or top and bottom margins by the given number of pixels.
"xinterval=30 yinterval=90" - Sets interval between numbers, major ticks and grid lines (default intervals are used if the custom intervals would be too dense or too sparse)
"xdecimals=2 ydecimals=-1" - Sets the minimum number of decimals; use negative numbers for scientific notation.
"msymbol=' \\u00d7" - Sets multiplication symbol for scientific notation, here a cross with spaces.
For an example, run the Help>Examples>Plots>Plot Results command. Requires 1.53a.
Plot.replace(index, type, xValues, yValues)
Replaces the plot object (curve, Label, etc.) with the specified index by points or a curve as specified in Plot.add(type, xValues, yValues).
Plot.useTemplate("plot name" or id)
Transfers the formatting of an open plot window to the current plot.
Plot.makeHighResolution(factor)
Creates a high-resolution image of the plot enlarged by factor. Add the second argument "disable" to avoid antialiased text. Plot.appendToStack
Appends the current plot to a virtual stack and resets. Must be called before Plot.show. For an example, run Help>Examples>Plots>Dynamic Plot.
Plot.show()
Displays the plot generated by Plot.create(), Plot.add(), etc. in a window. This function is automatically called when a macro exits.
Plot.update()
Draws the plot generated by Plot.create(), Plot.add(), etc. in an existing plot window. Equivalent to Plot.show if no plot window is open.
Plot.getValues(xpoints, ypoints)
Returns the values displayed by clicking on "List" in a plot or histogram window (example).
Plot.showValues()
Displays the plot values in the Results window using simple "X , Y, X1, Y1, .." column headings. Must be preceded by Plot.show.
Plot.showValuesWithLabels()
Displays the plot values in the Results window using the dataset labels, for example the labels supplied by Plot.setLegend. Must be preceded by Plot.show.
Plot.drawGrid()
Redraws the grid above previous plots.
Plot.drawShapes("rectangles", lefts, tops, rights, bottoms)
Draws one or more rectangles. The four arguments (values or arrays) hold rectangle coordinates.
Plot.drawBoxes("boxes width=30", x, y1, y2, y3, y4, y5)
Draws a boxplot, where 'width' is in pixels, array 'x' holds x-positions and arrays 'y1'..'y5' hold the quartile borders in ascending order. Secondary color will fill the box. For horizontal boxes, use "boxesx width=30" instead.
Plot.removeNaNs()
Removes NaN values from the plot. This has two effects: a) Numerical output via "List" or macro will be free of NaNs; b) Line plots that were interrupted by NaNs are now connected.
Plot.eneableLive(boolean)
Enables and disables the "Live" mode of the active plot. Requires 1.54e.
pow(base, exponent)
Returns the value of base raised to the power of exponent.

print(string)
Outputs a string to the "Log" window. Numeric arguments are automatically converted to strings. The print() function accepts multiple arguments. For example, you can use print(x, y, width, height) instead of print(x+" "+y+" "+width+" "+height). If the first argument is a file handle returned by File.open(path), then the second is saved in the refered file (see SaveTextFileDemo).

Numeric expressions are automatically converted to strings using four decimal places, or use the d2s function to specify the decimal places. For example, print(2/3) outputs "0.6667" but print(d2s(2/3, 1)) outputs "0.7".

The print() function accepts commands such as "\\Clear", "\\Update:<text>" and "\\Update<n>:<text>" (for n