The developer tools package on Mac OS X contains a very simple utility
called Icon Composer that converts images into Mac OS X-style
icon files. Using a standard graphics application, you can create art
for your icon, save it as a 32-bit image in TIFF, PICT, or Photoshop
format, then import it into Icon Composer. Once the image has been
imported, Icon Composer can create icon masks for icon sizes that
require one. Icon Composer saves files in the
format used by Mac OS X to store icon families. The Aqua Human
Interface Guidelines document (http://developer.apple.com/techpubs/macosx)
provides essential information about creating icons for Mac OS X.
For those comfortable working with Adobe Photoshop, this section
explains how to use that application to create source art for an icon
in just a few seconds. If you aren’t familiar with Photoshop, you can
ToDo.tiff file included with the sample
files, and skip the first four following steps:
Launch Photoshop and make a new a 128 × 128 pixel image with a transparent background.
Draw or copy/paste your art into the document.
Create a new image channel using the Channels tab. This new channel will function as an alpha mask. Paint the areas of the mask that you wish to be transparent in the Finder and in the Dock.
Save the file as a TIFF image. This is the recommended format for image files used in Cocoa.
Launch the Icon Composer application in
Choose Import Image from the ...