ImageJ & Fiji Bioimage Analysis

Public-domain Java image processing platform developed at the NIH for quantitative microscopy, densitometry, and live-cell tracking.

Specifications & Metrics

type: Bioimage Processing & Densitometry
language: Java (extensible via macros, Python/Jython, and SciJava plugins)
license: Public Domain (ImageJ 1.x) and BSD-2-Clause (ImageJ2 / Fiji)
developer: Wayne Rasband at the U.S. National Institutes of Health (released 1997, succeeding NIH Image) and LOCI (UW–Madison)

Created in 1997 by Wayne Rasband at the National Institutes of Health as a cross-platform Java successor to Macintosh NIH Image, ImageJ is developed in the public domain with an open plugin and macro architecture.
The Fiji distribution ("Fiji Is Just ImageJ") bundles Bio-Formats and hundreds of pre-installed life-science plugins for 3D confocal z-stack reconstruction, colocalization analysis, neurite tracing, and single-particle tracking.
In pharmacology laboratories, ImageJ is universally used to quantify Western blot band densitometry, wound-healing scratch-assay closure rates, immunofluorescence intensities, and calcium-imaging regions of interest (ROIs).