The Apple Icon Image format is the icon format used in Apple Inc.'s Mac OS X. It supports icons of 16×16, 32×32, 48×48, 128×128, 256×256 and 512×512 pixels, with both 1- and 8-bitalpha channel and multiple image states (example: open and closed folders). The fixed-size icons can be scaled by the operating system and displayed at any intermediate size.
The file format consists of an 8 byte header, followed by any number of icons.
Over the time the format have been improved and there is support for compression of some parts of the pixel data. The 32-bit ("is32", "il32", "ih32","it32") pixel data is offen compressed (per channel) with the PackBits algorithm.<br/>Some sources mentioned that the OS supports both compressed or uncompressed data chunks.
the values inside the brakets () in the length column is the uncompressed length.