A C++ library for processing PNG, capable of decompressing, rotating, pruning (compressing), and saving image.
buildTree: transform a given PNG image into internal representation for future processing
decompress: transform internal representation into a PNG image
prune: compress a given PNG image using a specified tolerance value
clockwiseRotate: rotate a given PNG image clockwise
getPixel: get pixel value at a specified location
A PNG image is first transformed into a quadtree before processing. Suppose we have an image of 128x128 pixels. In the following figure, the node at the green level of the tree corresponds to the entire 128x128 image; the nodes at the teal level of the tree correspond to the 64x64 partitions of the image; the nodes at the red level of the tree correspond to the 32x32 partitions of the image; the nodes at the black level of the tree correspond to the 16x16 partitions of the image; and so on. Each parent node can have either four or zero children.
This library is an example of how recursion can greatly simplify the code and improve the overally readability.