github.com/zebozhuang/go@v0.0.0-20200207033046-f8a98f6f5c5d/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 1.6.26.
     3  
     4  README.original gives the following license for those files:
     5  
     6  	Permission to use, copy, and distribute these images for any purpose
     7  	and without fee is hereby granted.
     8  
     9  The files basn0g01-30.png, basn0g02-29.png and basn0g04-31.png are in fact not
    10  part of pngsuite but were created from files in pngsuite. Their non-power-of-2
    11  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 by the
    17  sng command-line tool and some hand editing. The files basn0g0{1,2,4}.sng and
    18  ftbbn0g0{1,2,4}.sng were actually generated by first converting the PNG to a
    19  bitdepth of 8 and then running sng on them. basn4a08.sng was generated from a
    20  16-bit rgba version of basn4a08.png rather than the original gray + alpha.