Codec.Picture.Png

Module used for loading & writing 'Portable Network Graphics' (PNG) files. The API has two layers, the high level, which load the image without looking deeply about it and the low level, allowing access to data chunks contained in the PNG image.

For general use, please use decodePng function.

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

High level functions

class PngSavable a where

Encode an image into a png if possible.

Methods

encodePng :: Image a -> ByteString

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

Instances

PngSavable PixelRGBA8

PngSavable PixelRGB8

PngSavable Pixel8

decodePng :: ByteString -> Either String DynamicImage

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
• PixelYA8
• PixelRGB8
• PixelRGBA8

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

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

encodeDynamicPng :: DynamicImage -> Either String ByteString

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

• RGB8
• RGBA8
• Y8

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

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