ICO-PIL Windows Icon

Extensions: .ico

From the Pillow docs:

ICO is used to store icons on Windows. The largest available icon is read.

The save() method supports the following options:

A list of sizes including in this ico file; these are a 2-tuple, (width, height); Default to [(16, 16), (24, 24), (32, 32), (48, 48), (64, 64), (128, 128), (256, 256)]. Any sizes bigger than the original size or 256 will be ignored.


IM is a format used by LabEye and other applications based on the IFUNC image processing library. The library reads and writes most uncompressed interchange versions of this format.

IM is the only format that can store all internal PIL formats.

Parameters for reading

pilmode : str

From the Pillow documentation:

  • ‘L’ (8-bit pixels, grayscale)
  • ‘P’ (8-bit pixels, mapped to any other mode using a color palette)
  • ‘RGB’ (3x8-bit pixels, true color)
  • ‘RGBA’ (4x8-bit pixels, true color with transparency mask)
  • ‘CMYK’ (4x8-bit pixels, color separation)
  • ‘YCbCr’ (3x8-bit pixels, color video format)
  • ‘I’ (32-bit signed integer pixels)
  • ‘F’ (32-bit floating point pixels)

PIL also provides limited support for a few special modes, including ‘LA’ (‘L’ with alpha), ‘RGBX’ (true color with padding) and ‘RGBa’ (true color with premultiplied alpha).

When translating a color image to grayscale (mode ‘L’, ‘I’ or ‘F’), the library uses the ITU-R 601-2 luma transform:

L = R * 299/1000 + G * 587/1000 + B * 114/1000
as_gray : bool
If True, the image is converted using mode ‘F’. When mode is not None and as_gray is True, the image is first converted according to mode, and the result is then “flattened” using mode ‘F’.