This submodule keeps the PNM encode/decode capabilities
of the Image module.
PNM is a common image storage format on unix systems,
and is a very simple format.
This format doesn't use any color palette.
The format is divided into seven subformats;
P1(PBM) - ascii bitmap (only two colors)
P2(PGM) - ascii greymap (only grey levels)
P3(PPM) - ascii truecolor
P4(PBM) - binary bitmap
P5(PGM) - binary greymap
P6(PPM) - binary truecolor
P7 - binary truecolor (used by xv for thumbnails)
Simple encoding:
encode ,
encode_binary ,
encode_ascii
Simple decoding:
decode
Advanced encoding:
encode_P1 ,
encode_P2 ,
encode_P3 ,
encode_P4 ,
encode_P5 ,
encode_P6