Re: colo-hex

[Peter Rolf <indiego@gmx.net>]

[-- Attachment #1.1: Type: text/plain, Size: 1802 bytes --]

sorry, wrong version of test file. the right one is attached now.

Peter Rolf schrieb:
> 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
>
> ------------------------------------------------------------------------
>
> ___________________________________________________________________________________
> If your question is of interest to others as well, please add an entry to the Wiki!
>
> maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
> archive  : https://foundry.supelec.fr/projects/contextrev/
> wiki     : http://contextgarden.net
> ___________________________________________________________________________________


[-- Attachment #1.2: Type: text/html, Size: 2715 bytes --]

[-- Attachment #2: hex.tex --]
[-- Type: text/plain, Size: 677 bytes --]

\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) )


\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


[-- Attachment #3: Type: text/plain, Size: 487 bytes --]

___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : https://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________