Hi,
there is a small bug in colo-hex, which leads to slightly wrong colors
(at max. -0.390625%).
In line 41 of both mark related files there is
\newdimen\hexcolorfraction \hexcolorfraction=\dimexpr(1pt/256)
.
This should be 255 (#fractions) instead of 256 (#values); I made the
same error a quite while ago. If I patch the files, I get the correct
color in case of mark ii, but mark iv still gives the wrong one (remade
the formats). Mh, strange.
Here the output of my beloved 'tabbyCalc' (result of operation is always
in next line, which is then used for next operation):
1/255
0,0039215686*255
0,999999993
1/256
0,00390625*255
0,99609375-1*100
-0,390625
I attached a small test file, which hopefully 'shows' (depends on your
monitor) the difference. The border line goes from the lower left to the
upper right corner; you have to look 'closely'. :D
I case of pdftex you can also peek into the eps file to see the color
values (before and after patching). No such help for mkiv. I have no
clue why mkiv still gives the wrong color...
Best wishes, Peter
\setupcolors[state=start]
\setupcolor[hex]
%% fraction= 1/255*65536= 257.004
%\newdimen\hexcolorfraction \hexcolorfraction=\dimexpr1pt/255\relax% = 257sp
\definecolor[testcolor] [r=0.87843,g=0.87451,b=0.89020] % RGB(224,223,227))
\definecolor[testcolorHEX] [h=E0DFE3]% same as HEX (currently transformed to
RGB(223,222,226) )
\definecolor[testcolor] [r=1,g=1,b=1] % RGB(224,223,227))
\definecolor[testcolorHEX] [h=FFFFFF]% same as HEX (currently transformed to
RGB(223,222,226) )
\startMPpage
path p;
p:= unitsquare xyscaled(5cm,5cm);
fill (point 0 of p -- point 1 of p -- point 2 of p --cycle)
withcolor \MPcolor{testcolorHEX}; % bottom right part of the square
fill (point 0 of p -- point 3 of p -- point 2 of p --cycle)
withcolor \MPcolor{testcolor}; % top left part
\stopMPpage
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