It can display, edit, analyze, process, save and print 8-bit, 16-bit and 32-bit images. It can read many image formats including TIFF, GIF, JPEG, BMP, DICOM, FITS and "raw". It supports "stacks", a series of images that share a single window. It is multithreaded, so time-consuming operations such as image file reading can be performed in parallel with other operations.

It can calculate area and pixel value statistics of user-defined selections. It can measure distances and angles. It can create density histograms and line profile plots. It supports standard image processing functions such as contrast manipulation, sharpening, smoothing, edge detection and median filtering.

It does geometric transformations such as scaling, rotation and flips. Image can be zoomed up to 32:1 and down to 1:32. All analysis and processing functions are available at any magnification factor. The program supports any number of windows (images) simultaneously, limited only by available memory.

Spatial calibration is available to provide real world dimensional measurements in units such as millimeters. Density or gray scale calibration is also available.

ImageJ was designed with an open architecture that provides extensibility via Java plugins. Custom acquisition, analysis and processing plugins can be developed using ImageJ's built in editor and Java compiler. User-written plugins make it possible to solve almost any image processing or analysis problem.

ImageJ is being developed on Mac OS X using its built in editor and Java compiler, plus the BBEdit editor and the Ant build tool. The source code is freely available. The author, Wayne Rasband, is at the Research Services Branch, National Institute of Mental Health, Bethesda, Maryland, USA.

• Edit>Selection>Straighten works with stacks.
• Added an "Add to ROI Manager" option to the Edit>Options>Point Tool dialog box.
• The File>Import>Image Sequence "Convert to RGB" option now works with the "Use Virtual Stack" option.
• Added a "Convert to RGB" option to the dialog box displayed when a folder is dragged and dropped onto the "ImageJ" window.
• Edit>Draw displays a "Process Stack" dialog when operating on a stack. Use the "d" shortcut to avoid this dialog.
• Image>Show Info now displays the display range of 8-bit images.
• Process>FFT>Custom Filter now mirrors the image around its edges to avoid wrap around artifacts.
• The ROI Manager "Multi Measure" function now works with line and (single) point selections.
• Renamed the "Reset" button in the Analyze>Set Scale dialog to "Remove Scale" and changed the unit displayed with unscaled images from "cm" to "pixel".
• Image window activations are recorded.
• 16-bit composite color images are now correctly converted to 8-bits.
• Fixed a bug, introduced in 1.41n, that caused Process>Math>NaN Background to fail with stacks.
• Fixed a bug that caused Analyze>Tools>Calibration Bar to throw an exception on Windows if the default calibration bar was taller than the image.
• Fixed a bug that caused virtual stacks to hang if the backing folder contained images that were not all the same size and type.
• Fixed a bug that caused indexed 8-bit grayscale images to not be correctly converted to 16 and 32 bits.