# PNG-PIL Portable network graphics

Extensions: `.png`

A PNG format based on Pillow.

This format supports grayscale, RGB and RGBA images.

## Parameters for reading

ignoregammabool

  Avoid gamma correction. Default True.

pilmodestr

  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_graybool

  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

optimizebool

  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.