Legacy ImageMagick Discussions Archive

Well spotted. I have reported it: viewtopic.php?f=3&t=25633

Cool.
I will simply work with the swapped values meantime.

Thanks for the great help

The bug occurs when "m" and "y" are used explicitly. Compare and contrast:

convert xc:cmyk(10%,20%,30%,40%) -colorspace CMYK -precision 9 -format "%[fx:100*p{0,0}.c]\%,%[fx:100*p{0,0}.m]\%,%[fx:100*p{0,0}.y]\%,%[fx:100*p{0,0}.k]\%\n" info:

10.000763%,30.000763%,20%,40%

convert xc:cmyk(10%,20%,30%,40%) -colorspace CMYK -precision 9 -format "%[pixel:p{0,0}]\n" info:

cmyk(10.000763%,20%,30.000763%,40%)

EDIT: This is a reply to a post that then vanished.

Hi Everyone,

sorry for warming this thread up, but i ran into the same trouble with the exact behaviour.
I tried the upper commands and they work like expected, but the color seems not to be similar like photoshop.
If i run the following command i get cmyk(100,0,0,0) instead of cmyk(80,24,0,0):

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convert xc:rgb\(0,255,255\) -precision 9 -colorspace cmyk -format "%[fx:int(100*c)], %[fx:int(100*m)], %[fx:int(100*y)], %[fx:int(100*k)]\r\n" info:

can someone maybe share some insights how i get the right conversion like in the upper post from Tricon?

Thanks in advance,

See upthread. Tricon was using "-profile" for the conversions, not "-colorspace".

wow thanks for the fast reply!

i tried it also with the profile:

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convert xc:'rgb(0,255,255)' -profile AdobeRGB1998.icc -profile CoatedFOGRA39.icc -precision 9 -format "%[fx:int(100*c)], %[fx:int(100*m)], %[fx:int(100*y)], %[fx:int(100*k)]\r\n" info:

but if i do so, i get the following i get the following:

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convert: delegate library support not built-in `rgb(0,255,255)' (LCMS) @ warning/profile.c/ProfileImage/849.
convert: ColorSeparatedImageRequired `' @ error/fx.c/FxGetSymbol/1647.
0, 100, 100,

any ideas, what i can do?

What operating system are you using and what version of Imagemagick?

Have you tried something simple to ensure Imagemagick is working on your setup?

Hi Bonzo,

Its a Imagemagick on a OSX, handled over the Terminal-application. simple image generations are working.
Version: ImageMagick 6.9.1-4

Any ideas?

What does "convert -version" say? It should be something like:

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Version: ImageMagick 6.9.1--6 Q16 x64 2015-06-20 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2015 ImageMagick Studio LLC
License: http://www.imagemagick.org/script/license.php
Features: Cipher DPC Modules OpenMP
Delegates (built-in): bzlib cairo freetype jng jp2 jpeg lcms lqr openexr pangocairo png ps rsvg tiff webp xml zlib

If it doesn't say lcms under delegates, that's the problem.

Hi snibgo,

THX so much! after reinstall of ImageMagick with littleCMS it works like charme now!!

Ok, now i'm facing the last problem of the overall topic.

I get now from rgb(0,255,255) the following cmyk(56,0,18,0) value, what is obvious the right one like in photoshop.
But now i need to reconvert it into the right rgb value to visualize it to the customer.

i tried the following:

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convert xc:'cmyk(56,0,18,0)' -profile CoatedFOGRA39.icc -profile sRGB.icc -precision 9 -format "%[fx:int(100*r)], %[fx:int(100*g)], %[fx:int(100*b)]\r\n" info:

but it gives me rgb(81, 91, 94) back what is not correct. It should be something like rgb(85,198,212).

do anyone already figured out how this works?

Best,

The issue is that you have specified cmyk values in the range 0 to 255, but are requesting results in %. Note that in fx, r=u.r and either is in the range of 0 to 1. So your results are percent and not raw values. To get correspondence, multiply by 255 or use 100 and add %. I am using IM 6.9.1.10 Q16 Mac OSX

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convert xc:'cmyk(56,0,18,0)' \
-set colorspace CMYK -colorspace sRGB \
-precision 4 -format "%[fx:100*r]\%, %[fx:100*g]\%, %[fx:100*b]\%\n" info:

78.04%, 100%, 92.94%

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convert xc:'cmyk(56,0,18,0)' \
-set colorspace CMYK -colorspace sRGB \
-format "%[fx:int(255*r)], %[fx:int(255*g)], %[fx:int(255*b)]\n" info:

199, 255, 237

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convert xc:'cmyk(56,0,18,0)' \
-set colorspace CMYK -colorspace sRGB \
 %[pixel:u.p{0,0}]\n" info:

srgb(199,255,237)

All these results agree with results from the color converter at http://www.imagemagick.org/contrib/color-converter.php

Using profiles will give slightly different result, depending upon the profiles used. For example:

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convert xc:'cmyk(56,0,18,0)' \
-set colorspace CMYK -profile /users/fred/images/profiles/USWebCoatedSWOP.icc \
-profile /users/fred/images/profiles/sRGB.icc \
-format "%[fx:int(255*r)], %[fx:int(255*g)], %[fx:int(255*b)]\n" info:

195, 231, 235

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