PNG-PIL Portable network graphics

Extensions: .png

A PNG format based on Pillow.

This format supports grayscale, RGB and RGBA images.

Parameters for reading

ignoregamma : bool
Avoid gamma correction. Default False.
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’.

Parameters for saving

optimize : bool
If present and true, instructs the PNG writer to make the output file as small as possible. This includes extra processing in order to find optimal encoder settings.
transparency:
This option controls what color image to mark as transparent.
dpi: tuple of two scalars
The desired dpi in each direction.
pnginfo: PIL.PngImagePlugin.PngInfo
Object containing text tags.
compress_level: int
ZLIB compression level, a number between 0 and 9: 1 gives best speed, 9 gives best compression, 0 gives no compression at all. Default is 9. When optimize option is True compress_level has no effect (it is set to 9 regardless of a value passed).
compression: int
Compatibility with the freeimage PNG format. If given, it overrides compress_level.
icc_profile:
The ICC Profile to include in the saved file.
bits (experimental): int
This option controls how many bits to store. If omitted, the PNG writer uses 8 bits (256 colors).
quantize:
Compatibility with the freeimage PNG format. If given, it overrides bits. In this case, given as a number between 1-256.
dictionary (experimental): dict
Set the ZLIB encoder dictionary.