Apple Macintosh icons


Just like Windows icons, Mac OS X icons have several pages that depict the same content in different sizes, and perhaps in different color depths.

The default extension for the Apple Icon Image Format is ICNS.

Easy icon creation

  1. Open your existing image file.
  2. Should it have multiple pages or frames, select the desired page and frame.
  3. Choose the menu item Icon | Create Mac icon from image and check the boxes corresponding to the formats you want to create. Then click OK.
  4. Create Mac icon from image dialog

Testing your icon

Follow the same procedure as for Windows icons.


Size and color depth

There is a predefined list of page sizes and color depths that are allowed in ICNS. Only these are supported:

SizeColor depth
1024 x 102432-bit
512 x 512 (retina)32-bit
512 x 51232-bit
256 x 256 (retina)32-bit
256 x 25632-bit
128 x 12832-bit
64 x 64 (retina)32-bit
64 x 6432-bit
48 x 4832-bit
48 x 48256 colors
48 x 4816 colors
48 x 48Black and white
32 x 32 (retina)32-bit
32 x 3232-bit
32 x 32256 colors
32 x 3216 colors
32 x 32Black and white
16 x 1632-bit
16 x 16256 colors
16 x 1616 colors
16 x 16Black and white
16 x 12256 colors
16 x 1216 colors
16 x 12Black and white


16-color and 256-color Mac icons must have a standard palette. If editing such an icon, you can load the appropriate palette into the color picker by first switching to the swatch screen with the Toggle color panel button, then click and load Mac-16-colors.swa or Mac-256-colors.swa. This is how the standard 16-color and 256-color ICNS palettes look:

ICNS 16-color palette ICNS 256-color palette

Note that the 16-color palatte is not a subset of the 256-color palette.

Transparency mask

This limitation only applies to black and white, 16-color and 256-color pages.

The ICNS file format stores a common transparency mask for all paletted pages of the same given size. This means that, for example, the 48x48 1-bit page must always have the same alpha channel as the 48x48 16-color and 48x48 256-color pages.

Phantom page

This is more or less related to the transparency mask limitation.

Suppose that you have saved an ICNS document that has a 16-color or 256-color page but does not have a black-and-white (1-bit) page of the same size. When reloading the file, you will notice that an extra 1-bit page has appeared having that specific size, with all non-transparent pixels being black.

This is because the alpha channel of a 16- or 256-color ICNS page is stored in the same data stream as the corresponding 1-bit image, so the alpha mask cannot exist without a 1-bit page.

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