github.com/ccccaoqing/test@v0.0.0-20220510085219-3985d23445c0/src/image/png/testdata/pngsuite/README (about)

     1  The *.png and README.original files in this directory are copied from
     2  libpng.org, specifically contrib/pngsuite/* in libpng-1.2.40.tar.gz.
     3  README.original gives the following license for those files:
     4  
     5  	Permission to use, copy, and distribute these images for any purpose
     6  	and without fee is hereby granted.
     7  
     8  
     9  The files basn0g01-30.png, basn0g02-29.png and basn0g04-31.png are in fact
    10  not part of pngsuite but were created from files in pngsuite. Their non-power-
    11  of-two sizes makes them useful for testing bit-depths smaller than a byte.
    12  
    13  basn3a08.png was generated from basn6a08.png using the pngnq tool, which
    14  converted it to the 8-bit paletted image with alpha values in tRNS chunk.
    15  
    16  The *.sng files in this directory were generated from the *.png files
    17  by the sng command-line tool and some hand editing. The files
    18  basn0g0{1,2,4}.sng were actually generated by first converting the PNG
    19  to a bitdepth of 8 and then running sng on them. basn4a08.sng was generated
    20  by from a 16-bit rgba version of basn4a08.png rather than the original
    21  gray + alpha.