ImageJ is a Java-based image processing program developed at the National Institutes of Health and the Laboratory for Optical and Computational Instrumentation (LOCI, University of Wisconsin).

[5] Custom acquisition, analysis and processing plugins can be developed using ImageJ's built-in editor and a Java compiler.

[9] ImageJ's plugin architecture and built-in development environment has made it a popular platform for teaching image processing.

Downloadable distributions are available for Microsoft Windows, the classic Mac OS, macOS, Linux, and the Sharp Zaurus PDA.

ImageJ can display, edit, analyze, process, save, and print 8-bit color and grayscale, 16-bit integer, and 32-bit floating point images.