ImageJ is a freeware image processing tool inspired by NIH Image.
BS Editor: ImageJ is a freeware image processing tool inspired by NIH Image.

ImageJ Features
Open Source:
ImageJ and its Java source code are freely available and in the public domain. No license is required.
User Community:
ImageJ has a large and knowledgeable worldwide user community. More than 1700 users and developers subscribe to the ImageJ mailing list.
Macros:
Automate tasks and Create custom tools using macros. Automatically generate macro code using the command recorder. More than 300 macros are available on the ImageJ Web site.
Plugins:
Extend ImageJ by developing plugins using ImageJs built in text editor and Java compiler. More than 500 plugins are available.
Toolkit:
Use ImageJ as a image processing toolkit (class library) to develop applets, servlets or applications.
Speed:
ImageJ is the worlds fastest pure Java image processing program. It can filter a 2048x2048 image in 0.1 seconds (*). Thats 40 million pixels per second!
Data Types:
8-bit grayscale or indexed color, 16-bit unsigned integer, 32-bit floating-point and RGB color.
File Formats:
Open and save all supported data types as TIFF (uncompressed) or as raw data. Open and save GIF, JPEG, BMP, PNG, PGM, FITS and ASCII. Open Dicom. Open TIFFs, GIFs, JPEGs, DICOMs and raw data using a URL. Open and save many other formats using plugins.
Image display:
Tools are provided for zooming (1:32 to 32:1) and scrolling images. All analysis and processing functions work at any magnification Factor.
Selections:
Create rectangular, elliptical or irregular area selections. Create line and point selections. Edit selectoins and automatically create them using the wand tool. Draw, fill, clear, filter or measure selections. Save selections and transer them to other images.
Image Enhancement: you can free download ImageJ For OS Classic 1.36 now.