PIXELMATORThe incredibly affordable Pixelmator program offers Mac users a beautiful graphical interface and more than 20 tools for editing and retouching images, including brushes, transforming tools, selection tools, and layers and masks, not to mention 15 tools for color correction alone.
Pixelmator follows Photoshop's lead in its layout and layer-based image editing, but it performs layers and masking in a much simpler process, allowing you to drag and drop portions of an image to stack them together as editable layers. These layers then can be blended together with sliders for opacity and masking. There are more than 130 filters for adding effects to an image, and you can download others and produce your own with support for Apple's Quartz Composer filter editing and creation tool. The Photo Browser palette will give you access to libraries, events and albums in both iPhoto and Aperture, and the program publishes directly to Facebook, Flickr and Picasa. List Price: $59 (Mac only).
PICTURE WINDOW PRO 5.0MNow in its fifth edition, Picture Window Pro 5.0 from Digital Light & Color includes a Photoshop-like tool set, including curves adjustments, histograms, color management, black-and-white editing, resizing, masking, blurring, sharpening and much more.
Picture Window Pro 5.0 also offers its own features, like 2-zone and 3-zone adjustment transformations that enhance local contrast, brightness and saturation based on shadows, midtones and highlights. The program creates a workspace copy of your image so that you can compare and contrast changes as needed, and the History feature allows you to redo previous changes that are then updated on the adjustments you've made afterwards.
Just as in Photoshop, Picture Window Pro 5.0 creates sidecar files with image-adjustment information, and you can apply them to other images later. Photo-album and slideshow generators are included, as well. Unlike Photoshop, Picture Window Pro 5.0 is available for less than $100. List Price: $89 (Windows only).