Creates the PNG data structure out of an IndexedImage. This structure will have the minimum number of colors needed to represent the image faithfully in the file and will be ready for writing to a file.
This is called by writePng.
See Implementation
Creates the PNG data structure out of an IndexedImage. This structure will have the minimum number of colors needed to represent the image faithfully in the file and will be ready for writing to a file.
This is called by writePng.