我是 的粉丝potrace，最近读了Potrace 常见问题解答。
常见问题解答包括这样一句漂亮的话：
cat img.gif | giftopnm | ppmcolormask #641b1b | potrace
我正在寻找的命令将返回要解析的所有颜色的代码ppmcolormask。根据man ppmcolormask：它可能会返回：
You can specify color five ways:
o An X11-style color name (e.g. black).
o An X11-style hexadecimal specifier: rgb:r/g/b, where r g and b
are each 1- to 4-digit hexadecimal numbers.
o An X11-style decimal specifier: rgbi:r/g/b, where r g and b are
floating point numbers between 0 and 1.
o For backwards compatibility, an old-X11-style hexadecimal num‐
ber: #rgb, #rrggbb, #rrrgggbbb, or #rrrrggggbbbb.
o For backwards compatibility, a triplet of numbers separated by
commas: r,g,b, where r g and b are floating point numbers
between 0 and 1. (This style was added before MIT came up with
the similar rgbi style.)
答案1
cat foo.gif | giftopnm | ppmhist -noheader -hexcolors | awk '{ print "rgb:"$1"/"$2"/"$3 }'
将为您提供 X11 rgb:r/g/b 格式的所有颜色的列表。