iConStruct is a utility for programmers (REALBasic and others) that offers a simple way to Create icons of various sizes from a given picture file.
iConStruct automatically scales pictures to standard icon sizes and autmatically generates masks based on a specified brightness Threshold. For best results, the images that are to be converted to icons should be in front of a white (or very light) background. For 32-bit icon sets, the masks are generated as 8-bit grayscale images, and mask edges (1 Pixel wide) values are either set to the brightness of the corresponding pixels in the icon or a fixed value chosen by the user. 8-Bit icons are generated as dithered Versions of the 32-icons using web-safe color. The corresponding masks are generated as 1-bit B/W images. The icons and masks can be individually copied and pasted into other applications, or the entire set of icons can be saved as BMP files.