Each subsequent record (8 bytes each) maps

'Table of Contents' a list of all image types in the file, and their sizes (added in Mac OS X 10.7).Ī TOC is written out as an identifier (4 bytes) and size (4 bytes). Therefore, the supported OS version may not be accurate or adjusted based on file format. The support for newer image types seems to be introduced later than the key field (see previous two points).The 24-bit RGB icons ( is32, il32, ih32, it32) also allow images in JPEG 2000 and PNG format (tested on macOS 10.15.7 and macOS 11).Yet, even the ARGB keys can be displayed on macOS 10.15 if you set a JPEG 2000 or PNG image (see footnote on usage in app packages above). ARGB images are only supported in macOS 11 and newer – macOS 10.15.7 does not display ARGB images.the ARGB fields also accept files in PNG format – but not vice versa, you can not put ARGB images in any of the PNG-only fields (tested on macOS 11).The ARGB format consists of the ascii values for 'ARGB' and the four compressed channels tightly packed (see Compression).The it32 icon must start with a four-byte header, see footnote above. The 24-bit RGB format consists of the three compressed channels tightly packed (see Compression).The 4-bit an 8-bit icons use a fixed color palette with 16 colors and 256 colors respectively.Mono icons with alpha mask can display three colors: white, black, and transparent.These formats are supported in standalone icns files but do not display properly if used as application icon inside a. Usage unknown, the four zero-bytes can be any value and are quietly ignored. it32 data always starts with a header of four zero-bytes (tested all icns files in macOS 10.15.7 and macOS 11). The value inside the parenthesis is the uncompressed length for ARGB and 24-bit RGB icons. JPEG 2000 or PNG format 'retina' in 10.8)ĪRGB or JPEG 2000 † or PNG † format 'retina') JPEG 2000 † or PNG † format or 24-bit RGB icon Length of data, in bytes (including type and length), msb first The file format consists of an 8 byte header, followed by any number of icons. The fixed-size icons can be scaled by the operating system and displayed at any intermediate size.Īs of macOS 11, asset catalogs are the preferred file format for macOS custom icons instead. It supports icons of 16 × 16, 32 × 32, 48 × 48, 128 × 128, 256 × 256, 512 × 512 points at 1x and 2x scale, with both 1- and 8-bit alpha channels and multiple image states (example: open and closed folders). The Apple Icon Image format is an icon format used in Apple Inc.'s macOS.

Mac os folder icons png