JuicyPixels- Picture loading/serialization (in png, jpeg, bitmap, gif, tga, tiff and radiance)

Safe HaskellNone




Module used for loading & writing 'Portable Network Graphics' (PNG) files.

A high level API is provided. It loads and saves images for you while hiding all the details about PNG chunks.

Basic functions for PNG handling are decodePng, encodePng and encodePalettedPng. Convenience functions are provided for direct file handling and using DynamicImages.

The loader has been validated against the pngsuite (http:/www.libpng.orgpubpngpngsuite.html)


High level functions

class PngSavable a where Source

Encode an image into a png if possible.

Minimal complete definition



encodePng :: Image a -> ByteString Source

Transform an image into a png encoded bytestring, ready to be written as a file.

encodePngWithMetadata :: Metadatas -> Image a -> ByteString Source

Encode a png using some metadatas. The following metadata keys will be stored in a tEXt field :

the followings metadata will bes tored in the gAMA chunk.

The followings metadata will be stored in a pHYs chunk

decodePng :: ByteString -> Either String DynamicImage Source

Transform a raw png image to an image, without modifying the underlying pixel type. If the image is greyscale and < 8 bits, a transformation to RGBA8 is performed. This should change in the future. The resulting image let you manage the pixel types.

This function can output the following pixel types:

  • PixelY8

    • PixelY16
    • PixelYA8
    • PixelYA16
    • PixelRGB8
    • PixelRGB16
    • PixelRGBA8
    • PixelRGBA16

decodePngWithMetadata :: ByteString -> Either String (DynamicImage, Metadatas) Source

Same as decodePng but also extract meta datas present in the files.

writePng :: PngSavable pixel => FilePath -> Image pixel -> IO () Source

Helper function to directly write an image as a png on disk.

encodeDynamicPng :: DynamicImage -> Either String ByteString Source

Encode a dynamic image in bmp if possible, supported pixel type are :

  • Y8
  • Y16
  • YA8
  • YA16
  • RGB8
  • RGB16
  • RGBA8
  • RGBA16

encodePalettedPng :: Palette -> Image Pixel8 -> Either String ByteString Source

Encode a paletted image as a color indexed 8-bit PNG. the palette must have between 1 and 256 values in it.

writeDynamicPng :: FilePath -> DynamicImage -> IO (Either String Bool) Source

Write a dynamic image in a .png image file if possible. The same restriction as encodeDynamicPng apply.