Download

Platform Independent
To install ImageJ 1.45 on a computer with Java pre-installed, or to upgrade to the latest full distribution (including macros, plugins and LUTs), download ij145.zip (3.1MB) and extract the ImageJ directory. Use the Help>Update ImageJ command to upgrade to later versions.

Mac OS X
Download ImageJ 1.45 (5.5MB) as a double-clickable Mac OS X application. Includes ImageJ64, which uses Java 1.6 in 64-bit mode on Intel Macs running OS X 10.5 or later. (Instructions)

Linux
Download ImageJ 1.45 bundled with 32-bit Java (46MB) or with 64-bit Java (40MB). Both versions include Java 1.6.0_20 from Sun and the ImageJ source code. (Instructions)

Windows
Download ImageJ 1.45 bundled with 32-bit Java 1.6.0_20 (28MB), with 64-bit Java 1.6.0_20 (24MB; requires 64-bit Windows) or without Java (3MB). (Instructions)

Documentation
Tiago Ferreira's comprehensive The ImageJ User Guide is available as an 8MB PDF document. The JavaDoc API documentation (1.9MB ZIP archive) is also available.

Source Code
The ImageJ Java source consists of 92,000 lines of code in 265 files. It is available online and as a zip archives.

Example Images
31 downloadable sample images and stacks are available in ImageJ's File>Open Samples submenu. These images, and more, are also available as a 8.2MB zip archive.

You can also browse the ImageJ download directory at imagej.nih.gov/ij/download/. Refer to the release notes for a list of new features and bug fixes.