Free digital image editing software for mac

LiveQuartz is a nice and easy-to-use image editor. It is based on layers and CoreImage filters.
You have the layers at the left and the filters at the right of the window.
To edit an image, you can open it with LiveQuartz or drag and drop it into the central view of the window and it will be added as a new layer.
Main features:
- The brush allows you to paint with the color chosen at windows top right corner and with the tool size chosen beside.
- The eraser tool erases an image by replacing it by a transparent color. It uses the same tool size as the brush tool.
- The arrow is the layer moving tool.
- The text tool is for adding short texts. It is possible to modify the text by changing the layer name in layers list at the left of the window. You can also change the font of the newly inserted text with the button "Font" at the right of tools bar.
- The hand is for moving the view (for big images).
- The spiral tool is the tool you must use for filters. (when you select a filter that need to set a position, this tool is automatically activated)
- The selection tool is used to crop the image and to restrict painting area and erasing area.
- The magnifying glass is here to zoom and unZoom ("alt" key).

NIH Image is a public domain image processing and analysis program for the Macintosh.

Image can acquire, display, edit, enhance, analyze and animate images. It reads and writes TIFF, PICT, PICS and MacPaint files, providing compatibility with many other applications, including programs for scanning, processing, editing, publishing and analyzing images. It supports many standard image processing functions, including contrast enhancement, density profiling, smoothing, sharpening, edge detection, median filtering, and spatial convolution with user defined kernels.

Image can be used to measure area, mean, centroid, perimeter, etc. of user defined regions of interest. It also performs automated particle analysis and provides tools for measuring path lengths and angles. Spatial calibration is supported to provide real world area and length measurements. Density calibration can be done against radiation or optical density standards using user specified units. Results can be printed, exported to text files, or copied to the Clipboard.

A tool palette supports editing of color and gray scale images, including the ability to draw lines, rectangles and text. It can flip, rotate, invert and scale selections. It supports multiple windows and 8 levels of magnification. All editing, filtering, and measurement functions operate at any level of magnification and are undoable.

Image directly supports Data Translation and Scion frame grabber cards for capturing images or movie sequences using a TV camera. Acquired images can be shading corrected and frame averaged. Other frame grabbers are supported via plug-in modules.

Image can be customized in three ways: via a built-in Pascal-like macro language, via externally compiled plug-in modules and on the Pascal source code level.

Image Tricks 2.4.2 is a freeware application for editing your photos and images using Mac OS X Core Image filters that transform your photos and apply advanced visual effects. This program also contains a powerful image generator for. It uses Mac OS X Core Image filters that transform pictures to unimaginable extent. Various mathematical algorithms let you generate unique images. Created artwork can be used as a background, web-design illustration, for print materials and more.

Try the Freeware version and if you like it you can purchase a license code to activate Pro version filters and generators for just $14.95.

Major Features:

1. Easy to use and friendly Interface.
   
2. 63 Core Image Effects and Filters (72 in Pro version).
   
3. 12 image generators (19 in Pro version).
   
4. About 30 unique masks can be applied to an image.
   
5. Import over 20 image formats (TIFF, JPEG, GIF, PDF, EPS among them).
   
6. Export to TIFF, JPEG, PDF, PNG and GIF formats.
   
7. Resize and rotate images.
   
8. OpenGL acceleration supported.
   
9. iPhoto integration.
   
10. Universal Binary version allows to use it natively on both PowerPC and Intel-based
    
11. Macintosh computers.