A pure lua implementation of a PNG decoder

Usage

To initialize a new png image:

img = pngImage(<path to image>, newRowCallback)

The image will then be decoded. The available data from the image is as follows ``` img.width = 0 img.height = 0 img.depth = 0 img.colorType = 0

img:getPixel(x, y) ``` Decoding the image is synchronous, and will take a long time for large images.

Support

The supported colortypes are as follows:

• Grayscale
• Truecolor
• Indexed
• Greyscale/alpha
• Truecolor/alpha

So far the module only supports 256 Colors in png-8, png-24 as well as png-32 files. and no ancillary chunks.

More than 256 colors might be supported (Bit-depths over 8) as long as they align with whole bytes. These have not been tested.

Multiple IDAT chunks of arbitrary lengths are supported, as well as all filters.

Errors

So far no error-checking has been implemented. No crc32 checks are done.