IJ (ImageJ API)

java.lang.Object
- ij.IJ

```
public class IJ
extends Object
```
This class consists of static utility methods.

Nested Class Summary

Nested Classes
Modifier and Type Class Description

static interface IJ.ExceptionHandler

Nested Classes
Modifier and Type	Class	Description
`static interface`	`IJ.ExceptionHandler`

Field Summary

Fields
Modifier and Type	Field	Description
`static int`	`ALL_KEYS`
`static char`	`angstromSymbol`
`static int`	`CANCELED`
`static int`	`COLOR`	Image display modes
`static int`	`COMPOSITE`	Image display modes
`static boolean`	`debugMode`	Use setDebugMode(boolean) to enable/disable debug mode.
`static char`	`degreeSymbol`
`static int`	`GRAYSCALE`	Image display modes
`static boolean`	`hideProcessStackDialog`
`static char`	`micronSymbol`
`static String`	`URL`

Constructor Summary

Constructors
Constructor Description

IJ()

Constructors
Constructor	Description
`IJ()`

Method Summary

All Methods Static Methods Concrete Methods Deprecated Methods
Modifier and Type	Method	Description
`static void`	`addEventListener(IJEventListener listener)`
`static boolean`	`altKeyDown()`	Returns true if the alt key is down.
`static String`	`append(String string, String path)`	Appends a string to the end of a file.
`static void`	`beep()`	Emits an audio beep.
`static boolean`	`controlKeyDown()`	Returns true if the control key is down.
`static ImagePlus`	`createHyperStack(String title, int width, int height, int channels, int slices, int frames, int bitdepth)`	Creates a new hyperstack.
`static ImagePlus`	`createImage(String title, int width, int height, int depth, int bitdepth)`	Creates a new image.
`static ImagePlus`	`createImage(String title, String type, int width, int height, int depth)`	Creates a new imagePlus.
`static ImagePlus`	`createImage(String title, String type, int width, int height, int channels, int slices, int frames)`	Creates a new hyperstack.
`static long`	`currentMemory()`	Returns the amount of memory currently being used by ImageJ.
`static String`	`d2s(double n)`	Converts a number to a formatted string using 2 digits to the right of the decimal point.
`static String`	`d2s(double n, int decimalPlaces)`	Converts a number to a rounded formatted string.
`static String`	`d2s(double x, int significantDigits, int maxDigits)`	Converts a number to a rounded formatted string.
`static void`	`deleteRows(int row1, int row2)`	Deletes 'row1' through 'row2' of the "Results" window, where 'row1' and 'row2' must be in the range 0-Analyzer.getCounter()-1.
`static void`	`doCommand(ImagePlus imp, String command)`	Runs a menu command on a separete thread, using the specified image.
`static void`	`doCommand(String command)`	Runs a menu command on a separete thread and returns immediately.
`static int`	`doWand(int x, int y)`	Equivalent to clicking on the current image at (x,y) with the wand tool.
`static int`	`doWand(int x, int y, double tolerance, String mode)`	Traces the boundary of the area with pixel values within 'tolerance' of the value of the pixel at the starting location.
`static int`	`doWand(ImagePlus img, int x, int y, double tolerance, String mode)`	This version of doWand adds an ImagePlus argument.
`static void`	`error(String msg)`	Displays a message in a dialog box titled "ImageJ".
`static void`	`error(String title, String msg)`	Displays a message in a dialog box with the specified title.
`static boolean`	`escapePressed()`	Returns true if the `Esc` key was pressed since the last ImageJ command started to execute or since resetEscape() was called.
`static String`	`freeMemory()`	Runs the garbage collector and returns a string something like "64K of 256MB (25%)" that shows how much of the available memory is in use.
`static Applet`	`getApplet()`	Returns the Applet that created this ImageJ or null if running as an application.
`static ClassLoader`	`getClassLoader()`	Returns the class loader ImageJ uses to run plugins or the system class loader if Menus.getPlugInsPath() returns null.
`static String`	`getDir(String title)`	Alias for getDirectory().
`static String`	`getDirectory(String title)`	Returns the path to the home ("user.home"), startup, ImageJ, plugins, macros, luts, temp, current or image directory if `title` is "home", "startup", "imagej", "plugins", "macros", "luts", "temp", "current", "default", "image", otherwise, displays a dialog and returns the path to the directory selected by the user.
`static String`	`getErrorMessage()`	Returns the last error message written by IJ.error() or null if there was no error since the last time this method was called.
`static String`	`getFilePath(String dialogTitle)`	Displays an open file dialog and returns the path to the choosen file, or returns null if the dialog is canceled.
`static String`	`getFullVersion()`	Returns the ImageJ version and build number as a String, for example "1.46n05", or 1.46n99 if there is no build number.
`static ImagePlus`	`getImage()`	Returns a reference to the active image, or displays an error message and aborts the plugin or macro if no images are open.
`static ImageJ`	`getInstance()`	Returns a reference to the "ImageJ" frame.
`static String`	`getLog()`	Returns the contents of the Log window or null if the Log window is not open.
`static String[]`	`getLuts()`	Returns, as an array of strings, a list of the LUTs in the Image/Lookup Tables menu.
`static double`	`getNumber(String prompt, double defaultValue)`	Allows the user to enter a number in a dialog box.
`static ImageProcessor`	`getProcessor()`	Returns the active image or stack slice as an ImageProcessor, or displays an error message and aborts the plugin or macro if no images are open.
`static Object`	`getProperty(String key)`	Returns the object in IJ.properties associated with 'key', or null if 'key' is not found.
`static Dimension`	`getScreenSize()`	Returns the size, in pixels, of the primary display.
`static String`	`getString(String prompt, String defaultString)`	Allows the user to enter a string in a dialog box.
`static TextPanel`	`getTextPanel()`	Returns a reference to the "Results" window TextPanel.
`static String`	`getToolName()`	Returns the name of the current tool.
`static String`	`getVersion()`	Returns the ImageJ version number as a string.
`static void`	`handleException(Throwable e)`	Displays a stack trace.
`static boolean`	`is64Bit()`	Returns true if ImageJ is running a 64-bit version of Java.
`static boolean`	`isJava14()`	Always returns true.
`static boolean`	`isJava15()`	Always returns true.
`static boolean`	`isJava16()`	Returns true if ImageJ is running on a Java 1.6 or greater JVM.
`static boolean`	`isJava17()`	Returns true if ImageJ is running on a Java 1.7 or greater JVM.
`static boolean`	`isJava18()`	Returns true if ImageJ is running on a Java 1.8 or greater JVM.
`static boolean`	`isJava19()`	Returns true if ImageJ is running on a Java 1.9 or greater JVM.
`static boolean`	`isJava2()`	Always returns true.
`static boolean`	`isLinux()`	Returns true if ImageJ is running on Linux.
`static boolean`	`isMacintosh()`	Returns true if this machine is a Macintosh.
`static boolean`	`isMacOSX()`	Returns true if this machine is a Macintosh running OS X.
`static boolean`	`isMacro()`	Returns true if a macro is running, or if the run(), open() or newImage() method is executing.
`static boolean`	`isResultsWindow()`	Returns true if the "Results" window is open.
`static boolean`	`isVista()`	Obsolete; always returns false.
`static boolean`	`isWindows()`	Returns true if this machine is running Windows.
`static int`	`javaVersion()`	Returns the Java version (6, 7, 8, 9, 10, etc.).
`static void`	`log(String s)`
`static boolean`	`macroRunning()`	Returns true if the run(), open() or newImage() method is executing.
`static void`	`makeLine(double x1, double y1, double x2, double y2)`	Creates a straight line selection using floating point coordinates.
`static void`	`makeLine(int x1, int y1, int x2, int y2)`	Creates a straight line selection.
`static void`	`makeOval(double x, double y, double width, double height)`	Creates an subpixel resolution oval selection.
`static void`	`makeOval(int x, int y, int width, int height)`	Creates an oval selection.
`static void`	`makePoint(double x, double y)`	Creates a point selection using floating point coordinates.
`static void`	`makePoint(int x, int y)`	Creates a point selection using integer coordinates..
`static void`	`makeRectangle(double x, double y, double width, double height)`	Creates a subpixel resolution rectangular selection.
`static void`	`makeRectangle(int x, int y, int width, int height)`	Creates a rectangular selection.
`static long`	`maxMemory()`	Returns the maximum amount of memory available to ImageJ or zero if ImageJ is unable to determine this limit.
`static void`	`newImage(String title, String type, int width, int height, int depth)`	Opens a new image.
`static void`	`noImage()`	Displays a "no images are open" dialog box.
`static void`	`notifyEventListeners(int eventID)`
`static void`	`open()`	Displays a file open dialog box and then opens the tiff, dicom, fits, pgm, jpeg, bmp, gif, lut, roi, or text file selected by the user.
`static void`	`open(String path)`	Opens and displays a tiff, dicom, fits, pgm, jpeg, bmp, gif, lut, roi, or text file.
`static void`	`open(String path, int n)`	Opens and displays the nth image in the specified tiff stack.
`static String`	`openAsString(String path)`	Opens a text file as a string.
`static ImagePlus`	`openImage()`	Opens an image using a file open dialog and returns it as an ImagePlus object.
`static ImagePlus`	`openImage(String path)`	Opens the specified file as a tiff, bmp, dicom, fits, pgm, gif, jpeg or text image and returns an ImagePlus object if successful.
`static ImagePlus`	`openImage(String path, int n)`	Opens the nth image of the specified tiff stack.
`static String`	`openUrlAsString(String url)`	Opens a URL and returns the contents as a string.
`static ImagePlus`	`openVirtual(String path)`	Opens the specified tiff file as a virtual stack.
`static void`	`outOfMemory(String name)`	Displays an "out of memory" message to the "Log" window.
`static OvalRoi`	`OvalRoi(double x, double y, double width, double height)`	Creates an OvalRoi.
`static String`	`pad(int n, int digits)`	Pad 'n' with leading zeros to the specified number of digits.
`static void`	`redirectErrorMessages()`	Causes IJ.error() output to be temporarily redirected to the "Log" window.
`static void`	`redirectErrorMessages(boolean redirect)`	Set 'true' and IJ.error() output will be temporarily redirected to the "Log" window.
`static boolean`	`redirectingErrorMessages()`	Returns the state of the 'redirectErrorMessages' flag, which is set by File/Import/Image Sequence.
`static void`	`register(Class c)`	Adds the specified class to a Vector to keep it from being garbage collected, which would cause the classes static fields to be reset.
`static void`	`removeEventListener(IJEventListener listener)`
`static void`	`renameResults(String title)`	Renames a results window.
`static void`	`renameResults(String oldTitle, String newTitle)`	Changes the name of a table window from 'oldTitle' to 'newTitle'.
`static void`	`resetClassLoader()`
`static void`	`resetEscape()`	This method sets the `Esc` key to the "up" position.
`static void`	`resetMinAndMax()`	Resets the minimum and maximum displayed pixel values of the current image to be the same as the min and max pixel values.
`static void`	`resetMinAndMax(ImagePlus img)`	Resets the minimum and maximum displayed pixel values of the specified image to be the same as the min and max pixel values.
`static void`	`resetThreshold()`	Disables thresholding on the current image.
`static void`	`resetThreshold(ImagePlus img)`	Disables thresholding on the specified image.
`static Roi`	`Roi(double x, double y, double width, double height)`	Creates an Roi.
`static void`	`run(ImagePlus imp, String command, String options)`	Runs an ImageJ command using the specified image and options.
`static void`	`run(String command)`	Runs an ImageJ command.
`static void`	`run(String command, String options)`	Runs an ImageJ command, with options that are passed to the GenericDialog and OpenDialog classes.
`static String`	`runMacro(String macro)`	Runs the macro contained in the string `macro`.
`static String`	`runMacro(String macro, String arg)`	Runs the macro contained in the string `macro`.
`static String`	`runMacroFile(String name)`	Runs the specified macro file.
`static String`	`runMacroFile(String name, String arg)`	Runs the specified macro or script file in the current thread.
`static Object`	`runPlugIn(ImagePlus imp, String className, String arg)`	Runs the specified plugin using the specified image.
`static Object`	`runPlugIn(String className, String arg)`	Runs the specified plugin and returns a reference to it.
`static Object`	`runPlugIn(String commandName, String className, String arg)`	Runs the specified plugin and returns a reference to it.
`static void`	`save(ImagePlus imp, String path)`	Saves the specified image, lookup table or selection to the specified file path.
`static void`	`save(String path)`	Saves the current image, lookup table, selection or text window to the specified file path.
`static void`	`saveAs(ImagePlus imp, String format, String path)`
`static void`	`saveAs(String format, String path)`
`static boolean`	`saveAsTiff(ImagePlus imp, String path)`	Saves the specified image in TIFF format.
`static String`	`saveString(String string, String path)`	Saves a string as a file.
`static void`	`selectWindow(int id)`	For IDs less than zero, activates the image with the specified ID.
`static void`	`selectWindow(String title)`	Activates the window with the specified title.
`static void`	`setAutoThreshold(ImagePlus imp, String method)`
`static void`	`setBackgroundColor(int red, int green, int blue)`	Sets the background color.
`static void`	`setColumnHeadings(String headings)`	Clears the "Results" window and sets the column headings to those in the tab-delimited 'headings' String.
`static void`	`setDebugMode(boolean b)`	Enable/disable debug mode.
`static void`	`setExceptionHandler(IJ.ExceptionHandler handler)`	Installs a custom exception handler that overrides the handleException() method.
`static void`	`setForegroundColor(int red, int green, int blue)`	Sets the foreground color.
`static void`	`setInputEvent(InputEvent e)`
`static void`	`setKeyDown(int key)`
`static void`	`setKeyUp(int key)`
`static void`	`setMinAndMax(double min, double max)`	Sets the display range (minimum and maximum displayed pixel values) of the current image.
`static void`	`setMinAndMax(double min, double max, int channels)`	Sets the minimum and maximum displayed pixel values on the specified RGB channels, where 4=red, 2=green and 1=blue.
`static void`	`setMinAndMax(ImagePlus img, double min, double max)`	Sets the display range (minimum and maximum displayed pixel values) of the specified image.
`static void`	`setPasteMode(String mode)`	Sets the transfer mode used by the Edit/Paste command, where mode is "Copy", "Blend", "Average", "Difference", "Transparent", "Transparent2", "AND", "OR", "XOR", "Add", "Subtract", "Multiply", or "Divide".
`static void`	`setProperty(String key, Object value)`	Adds a key-value pair to IJ.properties.
`static void`	`setRawThreshold(ImagePlus img, double lowerThreshold, double upperThreshold, String displayMode)`	This is a version of setThreshold() that always uses raw (uncalibrated) values in the range 0-255 for 8-bit images and 0-65535 for 16-bit images.
`static void`	`setSlice(int slice)`	Switches to the specified stack slice, where 1<='slice'<=stack-size.
`static void`	`setTextPanel(TextPanel tp)`	TextWindow calls this method with a null argument when the "Results" window is closed.
`static void`	`setThreshold(double lowerThreshold, double upperThresold)`	Sets the lower and upper threshold levels and displays the image using red to highlight thresholded pixels.
`static void`	`setThreshold(double lowerThreshold, double upperThreshold, String displayMode)`	Sets the lower and upper threshold levels and displays the image using the specified `displayMode` ("Red", "Black & White", "Over/Under" or "No Update").
`static void`	`setThreshold(ImagePlus img, double lowerThreshold, double upperThreshold)`	Sets the lower and upper threshold levels of the specified image.
`static void`	`setThreshold(ImagePlus img, double lowerThreshold, double upperThreshold, String displayMode)`	Sets the lower and upper threshold levels of the specified image and updates the display using the specified `displayMode` ("Red", "Black & White", "Over/Under" or "No Update").
`static void`	`setTool(int id)`	Switches to the specified tool, where id = Toolbar.RECTANGLE (0), Toolbar.OVAL (1), etc.
`static boolean`	`setTool(String name)`	Switches to the specified tool, where 'name' is "rect", "elliptical", "brush", etc.
`static int`	`setupDialog(ImagePlus imp, int flags)`	Displays a "Process all images?" dialog.
`static boolean`	`shiftKeyDown()`	Returns true if the shift key is down.
`static void`	`showMessage(String msg)`	Displays a message in a dialog box titled "Message".
`static void`	`showMessage(String title, String msg)`	Displays a message in a dialog box with the specified title.
`static boolean`	`showMessageWithCancel(String title, String msg)`	Displays a message in a dialog box with the specified title.
`static void`	`showProgress(double progress)`	Updates the progress bar, where 0<=progress<=1.0.
`static void`	`showProgress(int currentIndex, int finalIndex)`	Updates the progress bar, where the length of the bar is set to (`currentValue+1)/finalValue` of the maximum bar length.
`static void`	`showStatus(String s)`	Displays a message in the ImageJ status bar.
`static void`	`showTime(ImagePlus imp, long start, String str)`
`static void`	`showTime(ImagePlus imp, long start, String str, int nslices)`
`static boolean`	`spaceBarDown()`	Returns true if the space bar is down.
`static void`	`suppressPluginNotFoundError()`	Temporarily suppress "plugin not found" errors.
`static String`	`time(ImagePlus imp, long startNanoTime)`	Experimental
`static boolean`	`versionLessThan(String version)`	Displays an error message and returns true if the ImageJ version is less than the one specified.
`static void`	`wait(int msecs)`	Delays 'msecs' milliseconds.
`static void`	`write(String s)`	Deprecated. replaced by IJ.log(), ResultsTable.setResult() and TextWindow.append().

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - COMPOSITE
```
public static final int COMPOSITE
```
    Image display modes
    
    See Also:
    
    Constant Field Values
  - COLOR
```
public static final int COLOR
```
    Image display modes
    
    See Also:
    
    Constant Field Values
  - GRAYSCALE
```
public static final int GRAYSCALE
```
    Image display modes
    
    See Also:
    
    Constant Field Values
  - URL
```
public static final String URL
```
    See Also:
    
    Constant Field Values
  - ALL_KEYS
```
public static final int ALL_KEYS
```
    See Also:
    
    Constant Field Values
  - debugMode
```
public static boolean debugMode
```
    Use setDebugMode(boolean) to enable/disable debug mode.
  - hideProcessStackDialog
```
public static boolean hideProcessStackDialog
```
  - micronSymbol
```
public static final char micronSymbol
```
    See Also:
    
    Constant Field Values
  - angstromSymbol
```
public static final char angstromSymbol
```
    See Also:
    
    Constant Field Values
  - degreeSymbol
```
public static final char degreeSymbol
```
    See Also:
    
    Constant Field Values
  - CANCELED
```
public static final int CANCELED
```
    See Also:
    
    Constant Field Values
- Constructor Detail
  - IJ
```
public IJ()
```
- Method Detail
  - getInstance
```
public static ImageJ getInstance()
```
    Returns a reference to the "ImageJ" frame.
  - setDebugMode
```
public static void setDebugMode(boolean b)
```
    Enable/disable debug mode.
  - runMacro
```
public static String runMacro(String macro)
```
    Runs the macro contained in the string macro. Returns any string value returned by the macro, null if the macro does not return a value, or "[aborted]" if the macro was aborted due to an error. The equivalent macro function is eval().
  - runMacro
```
public static String runMacro(String macro,
                              String arg)
```
    Runs the macro contained in the string macro. The optional string argument can be retrieved in the called macro using the getArgument() macro function. Returns any string value returned by the macro, null if the macro does not return a value, or "[aborted]" if the macro was aborted due to an error.
  - runMacroFile
```
public static String runMacroFile(String name,
                                  String arg)
```
    Runs the specified macro or script file in the current thread. The file is assumed to be in the macros folder unless name is a full path. The optional string argument (arg) can be retrieved in the called macro or script (v1.42k or later) using the getArgument() function. Returns any string value returned by the macro, or null. Scripts always return null. The equivalent macro function is runMacro().
  - runMacroFile
```
public static String runMacroFile(String name)
```
    Runs the specified macro file.
  - runPlugIn
```
public static Object runPlugIn(ImagePlus imp,
                               String className,
                               String arg)
```
    Runs the specified plugin using the specified image.
  - runPlugIn
```
public static Object runPlugIn(String className,
                               String arg)
```
    Runs the specified plugin and returns a reference to it.
  - runPlugIn
```
public static Object runPlugIn(String commandName,
                               String className,
                               String arg)
```
    Runs the specified plugin and returns a reference to it.
  - doCommand
```
public static void doCommand(String command)
```
    Runs a menu command on a separete thread and returns immediately.
  - doCommand
```
public static void doCommand(ImagePlus imp,
                             String command)
```
    Runs a menu command on a separete thread, using the specified image.
  - run
```
public static void run(String command)
```
    Runs an ImageJ command. Does not return until the command has finished executing. To avoid "image locked", errors, plugins that call this method should implement the PlugIn interface instead of PlugInFilter.
  - run
```
public static void run(String command,
                       String options)
```
    Runs an ImageJ command, with options that are passed to the GenericDialog and OpenDialog classes. Does not return until the command has finished executing. To generate run() calls, start the recorder (Plugins/Macro/Record) and run commands from the ImageJ menu bar.
  - run
```
public static void run(ImagePlus imp,
                       String command,
                       String options)
```
    Runs an ImageJ command using the specified image and options. To generate run() calls, start the recorder (Plugins/Macro/Record) and run commands from the ImageJ menu bar.
  - macroRunning
```
public static boolean macroRunning()
```
    Returns true if the run(), open() or newImage() method is executing.
  - isMacro
```
public static boolean isMacro()
```
    Returns true if a macro is running, or if the run(), open() or newImage() method is executing.
  - getApplet
```
public static Applet getApplet()
```
    Returns the Applet that created this ImageJ or null if running as an application.
  - showStatus
```
public static void showStatus(String s)
```
    Displays a message in the ImageJ status bar.
  - write
```
public static void write(String s)
```
    Deprecated.
    replaced by IJ.log(), ResultsTable.setResult() and TextWindow.append(). There are examples at http://imagej.nih.gov/ij/plugins/sine-cosine.html
  - log
```
public static void log(String s)
```
  - getLog
```
public static String getLog()
```
    Returns the contents of the Log window or null if the Log window is not open.
  - setColumnHeadings
```
public static void setColumnHeadings(String headings)
```
    Clears the "Results" window and sets the column headings to those in the tab-delimited 'headings' String. Writes to System.out.println if the "ImageJ" frame is not present.
  - isResultsWindow
```
public static boolean isResultsWindow()
```
    Returns true if the "Results" window is open.
  - renameResults
```
public static void renameResults(String title)
```
    Renames a results window.
  - renameResults
```
public static void renameResults(String oldTitle,
                                 String newTitle)
```
    Changes the name of a table window from 'oldTitle' to 'newTitle'.
  - deleteRows
```
public static void deleteRows(int row1,
                              int row2)
```
    Deletes 'row1' through 'row2' of the "Results" window, where 'row1' and 'row2' must be in the range 0-Analyzer.getCounter()-1.
  - getTextPanel
```
public static TextPanel getTextPanel()
```
    Returns a reference to the "Results" window TextPanel. Opens the "Results" window if it is currently not open. Returns null if the "ImageJ" window is not open.
  - setTextPanel
```
public static void setTextPanel(TextPanel tp)
```
    TextWindow calls this method with a null argument when the "Results" window is closed.
  - noImage
```
public static void noImage()
```
    Displays a "no images are open" dialog box.
  - outOfMemory
```
public static void outOfMemory(String name)
```
    Displays an "out of memory" message to the "Log" window.
  - showProgress
```
public static void showProgress(double progress)
```
    Updates the progress bar, where 0<=progress<=1.0. The progress bar is not shown in BatchMode and erased if progress>=1.0. The progress bar is updated only if more than 90 ms have passes since the last call. Does nothing if the ImageJ window is not present.
  - showProgress
```
public static void showProgress(int currentIndex,
                                int finalIndex)
```
    Updates the progress bar, where the length of the bar is set to (currentValue+1)/finalValue of the maximum bar length. The bar is erased if currentValue>=finalValue. The bar is updated only if more than 90 ms have passed since the last call. Does nothing if the ImageJ window is not present.
  - showMessage
```
public static void showMessage(String msg)
```
    Displays a message in a dialog box titled "Message". Writes the Java console if ImageJ is not present.
  - showMessage
```
public static void showMessage(String title,
                               String msg)
```
    Displays a message in a dialog box with the specified title. Displays HTML formatted text if 'msg' starts with "". There are examples at "http://imagej.nih.gov/ij/macros/HtmlDialogDemo.txt". Writes to the Java console if ImageJ is not present.
  - error
```
public static void error(String msg)
```
    Displays a message in a dialog box titled "ImageJ". If a macro is running, it is aborted. Writes to the Java console if the ImageJ window is not present.
  - error
```
public static void error(String title,
                         String msg)
```
    Displays a message in a dialog box with the specified title. If a macro is running, it is aborted. Writes to the Java console if ImageJ is not present.
  - getErrorMessage
```
public static String getErrorMessage()
```
    Returns the last error message written by IJ.error() or null if there was no error since the last time this method was called.
    
    See Also:
    
    error(String)
  - showMessageWithCancel
```
public static boolean showMessageWithCancel(String title,
                                            String msg)
```
    Displays a message in a dialog box with the specified title. Returns false if the user pressed "Cancel".
  - getNumber
```
public static double getNumber(String prompt,
                               double defaultValue)
```
    Allows the user to enter a number in a dialog box. Returns the value IJ.CANCELED (-2,147,483,648) if the user cancels the dialog box. Returns 'defaultValue' if the user enters an invalid number.
  - getString
```
public static String getString(String prompt,
                               String defaultString)
```
    Allows the user to enter a string in a dialog box. Returns "" if the user cancels the dialog box.
  - wait
```
public static void wait(int msecs)
```
    Delays 'msecs' milliseconds.
  - beep
```
public static void beep()
```
    Emits an audio beep.
  - freeMemory
```
public static String freeMemory()
```
    Runs the garbage collector and returns a string something like "64K of 256MB (25%)" that shows how much of the available memory is in use. This is the string displayed when the user clicks in the status bar.
  - currentMemory
```
public static long currentMemory()
```
    Returns the amount of memory currently being used by ImageJ.
  - maxMemory
```
public static long maxMemory()
```
    Returns the maximum amount of memory available to ImageJ or zero if ImageJ is unable to determine this limit.
  - showTime
```
public static void showTime(ImagePlus imp,
                            long start,
                            String str)
```
  - showTime
```
public static void showTime(ImagePlus imp,
                            long start,
                            String str,
                            int nslices)
```
  - time
```
public static String time(ImagePlus imp,
                          long startNanoTime)
```
    Experimental
  - d2s
```
public static String d2s(double n)
```
    Converts a number to a formatted string using 2 digits to the right of the decimal point.
  - d2s
```
public static String d2s(double n,
                         int decimalPlaces)
```
    Converts a number to a rounded formatted string. The 'decimalPlaces' argument specifies the number of digits to the right of the decimal point (0-9). Uses scientific notation if 'decimalPlaces is negative.
  - d2s
```
public static String d2s(double x,
                         int significantDigits,
                         int maxDigits)
```
    Converts a number to a rounded formatted string. The 'significantDigits' argument specifies the minimum number of significant digits, which is also the preferred number of digits behind the decimal. Fewer decimals are shown if the number would have more than 'maxDigits'. Exponential notation is used if more than 'maxDigits' would be needed.
  - pad
```
public static String pad(int n,
                         int digits)
```
    Pad 'n' with leading zeros to the specified number of digits.
  - register
```
public static void register(Class c)
```
    Adds the specified class to a Vector to keep it from being garbage collected, which would cause the classes static fields to be reset. Probably not needed with Java 1.2 or later.
  - spaceBarDown
```
public static boolean spaceBarDown()
```
    Returns true if the space bar is down.
  - controlKeyDown
```
public static boolean controlKeyDown()
```
    Returns true if the control key is down.
  - altKeyDown
```
public static boolean altKeyDown()
```
    Returns true if the alt key is down.
  - shiftKeyDown
```
public static boolean shiftKeyDown()
```
    Returns true if the shift key is down.
  - setKeyDown
```
public static void setKeyDown(int key)
```
  - setKeyUp
```
public static void setKeyUp(int key)
```
  - setInputEvent
```
public static void setInputEvent(InputEvent e)
```
  - isMacintosh
```
public static boolean isMacintosh()
```
    Returns true if this machine is a Macintosh.
  - isMacOSX
```
public static boolean isMacOSX()
```
    Returns true if this machine is a Macintosh running OS X.
  - isWindows
```
public static boolean isWindows()
```
    Returns true if this machine is running Windows.
  - javaVersion
```
public static int javaVersion()
```
    Returns the Java version (6, 7, 8, 9, 10, etc.).
  - isJava2
```
public static boolean isJava2()
```
    Always returns true.
  - isJava14
```
public static boolean isJava14()
```
    Always returns true.
  - isJava15
```
public static boolean isJava15()
```
    Always returns true.
  - isJava16
```
public static boolean isJava16()
```
    Returns true if ImageJ is running on a Java 1.6 or greater JVM.
  - isJava17
```
public static boolean isJava17()
```
    Returns true if ImageJ is running on a Java 1.7 or greater JVM.
  - isJava18
```
public static boolean isJava18()
```
    Returns true if ImageJ is running on a Java 1.8 or greater JVM.
  - isJava19
```
public static boolean isJava19()
```
    Returns true if ImageJ is running on a Java 1.9 or greater JVM.
  - isLinux
```
public static boolean isLinux()
```
    Returns true if ImageJ is running on Linux.
  - isVista
```
public static boolean isVista()
```
    Obsolete; always returns false.
  - is64Bit
```
public static boolean is64Bit()
```
    Returns true if ImageJ is running a 64-bit version of Java.
  - versionLessThan
```
public static boolean versionLessThan(String version)
```
    Displays an error message and returns true if the ImageJ version is less than the one specified.
  - setupDialog
```
public static int setupDialog(ImagePlus imp,
                              int flags)
```
    Displays a "Process all images?" dialog. Returns 'flags'+PlugInFilter.DOES_STACKS if the user selects "Yes", 'flags' if the user selects "No" and PlugInFilter.DONE if the user selects "Cancel".
  - makeRectangle
```
public static void makeRectangle(int x,
                                 int y,
                                 int width,
                                 int height)
```
    Creates a rectangular selection. Removes any existing selection if width or height are less than 1.
  - makeRectangle
```
public static void makeRectangle(double x,
                                 double y,
                                 double width,
                                 double height)
```
    Creates a subpixel resolution rectangular selection.
  - makeOval
```
public static void makeOval(int x,
                            int y,
                            int width,
                            int height)
```
    Creates an oval selection. Removes any existing selection if width or height are less than 1.
  - makeOval
```
public static void makeOval(double x,
                            double y,
                            double width,
                            double height)
```
    Creates an subpixel resolution oval selection.
  - makeLine
```
public static void makeLine(int x1,
                            int y1,
                            int x2,
                            int y2)
```
    Creates a straight line selection.
  - makeLine
```
public static void makeLine(double x1,
                            double y1,
                            double x2,
                            double y2)
```
    Creates a straight line selection using floating point coordinates.
  - makePoint
```
public static void makePoint(int x,
                             int y)
```
    Creates a point selection using integer coordinates..
  - makePoint
```
public static void makePoint(double x,
                             double y)
```
    Creates a point selection using floating point coordinates.
  - Roi
```
public static Roi Roi(double x,
                      double y,
                      double width,
                      double height)
```
    Creates an Roi.
  - OvalRoi
```
public static OvalRoi OvalRoi(double x,
                              double y,
                              double width,
                              double height)
```
    Creates an OvalRoi.
  - setMinAndMax
```
public static void setMinAndMax(double min,
                                double max)
```
    Sets the display range (minimum and maximum displayed pixel values) of the current image.
  - setMinAndMax
```
public static void setMinAndMax(ImagePlus img,
                                double min,
                                double max)
```
    Sets the display range (minimum and maximum displayed pixel values) of the specified image.
  - setMinAndMax
```
public static void setMinAndMax(double min,
                                double max,
                                int channels)
```
    Sets the minimum and maximum displayed pixel values on the specified RGB channels, where 4=red, 2=green and 1=blue.
  - resetMinAndMax
```
public static void resetMinAndMax()
```
    Resets the minimum and maximum displayed pixel values of the current image to be the same as the min and max pixel values.
  - resetMinAndMax
```
public static void resetMinAndMax(ImagePlus img)
```
    Resets the minimum and maximum displayed pixel values of the specified image to be the same as the min and max pixel values.
  - setThreshold
```
public static void setThreshold(double lowerThreshold,
                                double upperThresold)
```
    Sets the lower and upper threshold levels and displays the image using red to highlight thresholded pixels. May not work correctly on 16 and 32 bit images unless the display range has been reset using IJ.resetMinAndMax().
  - setThreshold
```
public static void setThreshold(double lowerThreshold,
                                double upperThreshold,
                                String displayMode)
```
    Sets the lower and upper threshold levels and displays the image using the specified displayMode ("Red", "Black & White", "Over/Under" or "No Update").
  - setThreshold
```
public static void setThreshold(ImagePlus img,
                                double lowerThreshold,
                                double upperThreshold)
```
    Sets the lower and upper threshold levels of the specified image.
  - setThreshold
```
public static void setThreshold(ImagePlus img,
                                double lowerThreshold,
                                double upperThreshold,
                                String displayMode)
```
    Sets the lower and upper threshold levels of the specified image and updates the display using the specified displayMode ("Red", "Black & White", "Over/Under" or "No Update"). With calibrated images, 'lowerThreshold' and 'upperThreshold' must be density calibrated values. Use setRawThreshold() to set the threshold using raw (uncalibrated) values.
  - setRawThreshold
```
public static void setRawThreshold(ImagePlus img,
                                   double lowerThreshold,
                                   double upperThreshold,
                                   String displayMode)
```
    This is a version of setThreshold() that always uses raw (uncalibrated) values in the range 0-255 for 8-bit images and 0-65535 for 16-bit images.
  - setAutoThreshold
```
public static void setAutoThreshold(ImagePlus imp,
                                    String method)
```
  - resetThreshold
```
public static void resetThreshold()
```
    Disables thresholding on the current image.
  - resetThreshold
```
public static void resetThreshold(ImagePlus img)
```
    Disables thresholding on the specified image.
  - selectWindow
```
public static void selectWindow(int id)
```
    For IDs less than zero, activates the image with the specified ID. For IDs greater than zero, activates the Nth image.
  - selectWindow
```
public static void selectWindow(String title)
```
    Activates the window with the specified title.
  - setForegroundColor
```
public static void setForegroundColor(int red,
                                      int green,
                                      int blue)
```
    Sets the foreground color.
  - setBackgroundColor
```
public static void setBackgroundColor(int red,
                                      int green,
                                      int blue)
```
    Sets the background color.
  - setTool
```
public static void setTool(int id)
```
    Switches to the specified tool, where id = Toolbar.RECTANGLE (0), Toolbar.OVAL (1), etc.
  - setTool
```
public static boolean setTool(String name)
```
    Switches to the specified tool, where 'name' is "rect", "elliptical", "brush", etc. Returns 'false' if the name is not recognized.
  - getToolName
```
public static String getToolName()
```
    Returns the name of the current tool.
  - doWand
```
public static int doWand(int x,
                         int y)
```
    Equivalent to clicking on the current image at (x,y) with the wand tool. Returns the number of points in the resulting ROI.
  - doWand
```
public static int doWand(int x,
                         int y,
                         double tolerance,
                         String mode)
```
    Traces the boundary of the area with pixel values within 'tolerance' of the value of the pixel at the starting location. 'tolerance' is in uncalibrated units. 'mode' can be "4-connected", "8-connected" or "Legacy". "Legacy" is for compatibility with previous versions of ImageJ; it is ignored if 'tolerance' > 0.
  - doWand
```
public static int doWand(ImagePlus img,
                         int x,
                         int y,
                         double tolerance,
                         String mode)
```
    This version of doWand adds an ImagePlus argument.
  - setPasteMode
```
public static void setPasteMode(String mode)
```
    Sets the transfer mode used by the Edit/Paste command, where mode is "Copy", "Blend", "Average", "Difference", "Transparent", "Transparent2", "AND", "OR", "XOR", "Add", "Subtract", "Multiply", or "Divide".
  - getImage
```
public static ImagePlus getImage()
```
    Returns a reference to the active image, or displays an error message and aborts the plugin or macro if no images are open.
  - getProcessor
```
public static ImageProcessor getProcessor()
```
    Returns the active image or stack slice as an ImageProcessor, or displays an error message and aborts the plugin or macro if no images are open.
  - setSlice
```
public static void setSlice(int slice)
```
    Switches to the specified stack slice, where 1<='slice'<=stack-size.
  - getVersion
```
public static String getVersion()
```
    Returns the ImageJ version number as a string.
  - getFullVersion
```
public static String getFullVersion()
```
    Returns the ImageJ version and build number as a String, for example "1.46n05", or 1.46n99 if there is no build number.
  - getDirectory
```
public static String getDirectory(String title)
```
    Returns the path to the home ("user.home"), startup, ImageJ, plugins, macros, luts, temp, current or image directory if title is "home", "startup", "imagej", "plugins", "macros", "luts", "temp", "current", "default", "image", otherwise, displays a dialog and returns the path to the directory selected by the user. Returns null if the specified directory is not found or the user cancels the dialog box. Also aborts the macro if the user cancels the dialog box.
  - getDir
```
public static String getDir(String title)
```
    Alias for getDirectory().
  - getFilePath
```
public static String getFilePath(String dialogTitle)
```
    Displays an open file dialog and returns the path to the choosen file, or returns null if the dialog is canceled.
  - open
```
public static void open()
```
    Displays a file open dialog box and then opens the tiff, dicom, fits, pgm, jpeg, bmp, gif, lut, roi, or text file selected by the user. Displays an error message if the selected file is not in one of the supported formats, or if it is not found.
  - open
```
public static void open(String path)
```
    Opens and displays a tiff, dicom, fits, pgm, jpeg, bmp, gif, lut, roi, or text file. Displays an error message if the specified file is not in one of the supported formats, or if it is not found. With 1.41k or later, opens images specified by a URL.
  - open
```
public static void open(String path,
                        int n)
```
    Opens and displays the nth image in the specified tiff stack.
  - openImage
```
public static ImagePlus openImage(String path)
```
    Opens the specified file as a tiff, bmp, dicom, fits, pgm, gif, jpeg or text image and returns an ImagePlus object if successful. Calls HandleExtraFileTypes plugin if the file type is not recognised. Displays a file open dialog if 'path' is null or an empty string. Note that 'path' can also be a URL. Some reader plugins, including the Bio-Formats plugin, display the image and return null. Use IJ.open() to display a file open dialog box.
  - openImage
```
public static ImagePlus openImage(String path,
                                  int n)
```
    Opens the nth image of the specified tiff stack.
  - openVirtual
```
public static ImagePlus openVirtual(String path)
```
    Opens the specified tiff file as a virtual stack.
  - openImage
```
public static ImagePlus openImage()
```
    Opens an image using a file open dialog and returns it as an ImagePlus object.
  - openUrlAsString
```
public static String openUrlAsString(String url)
```
    Opens a URL and returns the contents as a string. Returns "" if there an error, including host or file not found.
  - save
```
public static void save(String path)
```
    Saves the current image, lookup table, selection or text window to the specified file path. The path must end in ".tif", ".jpg", ".gif", ".zip", ".raw", ".avi", ".bmp", ".fits", ".pgm", ".png", ".lut", ".roi" or ".txt".
  - save
```
public static void save(ImagePlus imp,
                        String path)
```
    Saves the specified image, lookup table or selection to the specified file path. The file path should end with ".tif", ".jpg", ".gif", ".zip", ".raw", ".avi", ".bmp", ".fits", ".pgm", ".png", ".lut", ".roi" or ".txt". The specified image is saved in TIFF format if there is no extension.
  - saveAs
```
public static void saveAs(String format,
                          String path)
```
  - saveAs
```
public static void saveAs(ImagePlus imp,
                          String format,
                          String path)
```
  - saveAsTiff
```
public static boolean saveAsTiff(ImagePlus imp,
                                 String path)
```
    Saves the specified image in TIFF format. Displays a file save dialog if 'path' is null or an empty string. Returns 'false' if there is an error or if the user selects "Cancel" in the file save dialog.
  - saveString
```
public static String saveString(String string,
                                String path)
```
    Saves a string as a file. Displays a file save dialog if 'path' is null or blank. Returns an error message if there is an exception, otherwise returns null.
  - append
```
public static String append(String string,
                            String path)
```
    Appends a string to the end of a file. A newline character ("\n") is added to the end of the string before it is written. Returns an error message if there is an exception, otherwise returns null.
  - openAsString
```
public static String openAsString(String path)
```
    Opens a text file as a string. Displays a file open dialog if path is null or blank. Returns null if the user cancels the file open dialog. If there is an error, returns a message in the form "Error: message".
  - createImage
```
public static ImagePlus createImage(String title,
                                    int width,
                                    int height,
                                    int depth,
                                    int bitdepth)
```
    Creates a new image.
    
    Parameters:
    
    title - image name
    
    width - image width in pixels
    
    height - image height in pixels
    
    depth - number of stack images
    
    bitdepth - 8, 16, 32 (float) or 24 (RGB)
  - createImage
```
public static ImagePlus createImage(String title,
                                    String type,
                                    int width,
                                    int height,
                                    int depth)
```
    Creates a new imagePlus. Type should contain "8-bit", "16-bit", "32-bit" or "RGB". In addition, it can contain "white", "black" or "ramp". Width and height specify the width and height of the image in pixels. Depth specifies the number of stack slices.
  - createImage
```
public static ImagePlus createImage(String title,
                                    String type,
                                    int width,
                                    int height,
                                    int channels,
                                    int slices,
                                    int frames)
```
    Creates a new hyperstack.
    
    Parameters:
    
    title - image name
    
    type - "8-bit", "16-bit", "32-bit" or "RGB". May also contain "white" , "black" (the default), "ramp", "composite-mode", "color-mode", "grayscale-mode or "label".
    
    width - image width in pixels
    
    height - image height in pixels
    
    channels - number of channels
    
    slices - number of slices
    
    frames - number of frames
  - createHyperStack
```
public static ImagePlus createHyperStack(String title,
                                         int width,
                                         int height,
                                         int channels,
                                         int slices,
                                         int frames,
                                         int bitdepth)
```
    Creates a new hyperstack.
    
    Parameters:
    
    title - image name
    
    width - image width in pixels
    
    height - image height in pixels
    
    channels - number of channels
    
    slices - number of slices
    
    frames - number of frames
    
    bitdepth - 8, 16, 32 (float) or 24 (RGB)
  - newImage
```
public static void newImage(String title,
                            String type,
                            int width,
                            int height,
                            int depth)
```
    Opens a new image. Type should contain "8-bit", "16-bit", "32-bit" or "RGB". In addition, it can contain "white", "black" or "ramp". Width and height specify the width and height of the image in pixels. Depth specifies the number of stack slices.
  - escapePressed
```
public static boolean escapePressed()
```
    Returns true if the Esc key was pressed since the last ImageJ command started to execute or since resetEscape() was called.
  - resetEscape
```
public static void resetEscape()
```
    This method sets the Esc key to the "up" position. The Executer class calls this method when it runs an ImageJ command in a separate thread.
  - redirectErrorMessages
```
public static void redirectErrorMessages()
```
    Causes IJ.error() output to be temporarily redirected to the "Log" window.
  - redirectErrorMessages
```
public static void redirectErrorMessages(boolean redirect)
```
    Set 'true' and IJ.error() output will be temporarily redirected to the "Log" window.
  - redirectingErrorMessages
```
public static boolean redirectingErrorMessages()
```
    Returns the state of the 'redirectErrorMessages' flag, which is set by File/Import/Image Sequence.
  - suppressPluginNotFoundError
```
public static void suppressPluginNotFoundError()
```
    Temporarily suppress "plugin not found" errors.
  - getClassLoader
```
public static ClassLoader getClassLoader()
```
    Returns the class loader ImageJ uses to run plugins or the system class loader if Menus.getPlugInsPath() returns null.
  - getScreenSize
```
public static Dimension getScreenSize()
```
    Returns the size, in pixels, of the primary display.
  - getLuts
```
public static String[] getLuts()
```
    Returns, as an array of strings, a list of the LUTs in the Image/Lookup Tables menu.
  - resetClassLoader
```
public static void resetClassLoader()
```
  - handleException
```
public static void handleException(Throwable e)
```
    Displays a stack trace. Use the setExceptionHandler method() to override with a custom exception handler.
  - setExceptionHandler
```
public static void setExceptionHandler(IJ.ExceptionHandler handler)
```
    Installs a custom exception handler that overrides the handleException() method.
  - addEventListener
```
public static void addEventListener(IJEventListener listener)
```
  - removeEventListener
```
public static void removeEventListener(IJEventListener listener)
```
  - notifyEventListeners
```
public static void notifyEventListeners(int eventID)
```
  - setProperty
```
public static void setProperty(String key,
                               Object value)
```
    Adds a key-value pair to IJ.properties. The key and value are removed if 'value' is null.
  - getProperty
```
public static Object getProperty(String key)
```
    Returns the object in IJ.properties associated with 'key', or null if 'key' is not found.

Class IJ

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

COMPOSITE

COLOR

GRAYSCALE

URL

ALL_KEYS

debugMode

hideProcessStackDialog

micronSymbol

angstromSymbol

degreeSymbol

CANCELED

Constructor Detail

IJ

Method Detail

getInstance

setDebugMode

runMacro

runMacro

runMacroFile

runMacroFile

runPlugIn

runPlugIn

runPlugIn

doCommand

doCommand

run

run

run

macroRunning

isMacro

getApplet

showStatus

write

log

getLog

setColumnHeadings

isResultsWindow

renameResults

renameResults

deleteRows

getTextPanel

setTextPanel

noImage

outOfMemory

showProgress

showProgress

showMessage

showMessage

error

error

getErrorMessage

showMessageWithCancel

getNumber

getString

wait

beep

freeMemory

currentMemory

maxMemory

showTime

showTime

time

d2s

d2s

d2s

pad

register

spaceBarDown

controlKeyDown

altKeyDown

shiftKeyDown

setKeyDown

setKeyUp