Process the auxillary “bKGD” chunk

Handles

The Average filter computes value for a pixel based on the average between the pixel to its left and the pixel directly above it

The Sub filter transmits the difference between each byte and the value of the corresponding byte of the prior pixel

The Up filter transmits the difference between each byte and the value of the corresponding byte of the same pixel in the row above it

A module for extracting and storing scanlines from images based on their interlace method

Methods for decoding and encoding Adam7 interlacing. Credit to the Ruby ChunkyPNG project for bitwisdom

Module for handling PNG-specific behaviour of Adam7

Packing and unpacking palettes