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Old 10-08-2014, 08:02 AM   #1
Pedroski
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inkscape and colours


My son asked me to make some certificates to give to his students. I said start skype and inkscape. I told him to draw some squares to show me the colours he wanted, then go to the fill dialogue.

His first colour was light blue. I said go to the CMYK tab in the fill dialogue and tell me the values.

He had: C=27,M=27, Y=0, K=11, A=100

I said that gives me a bluish-grey, not a light blue.

I thought these values were absolute. They are not.

How does that figure?? Depends on what?
 
Old 10-08-2014, 08:47 AM   #2
jlinkels
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They are absolute.

But I can tell you C=27, M=27 Y=0 does not give you a blue color, ever.

Cyan is bluish, so this should be the largest number.
(0,0,0) is white.
(27,0,0) is light cyan
To get a light blue you would need something like (60,10,0)
Equal values of C and M will always give you a shade of purple.
Add some K to this vector and the color will move to grey as you add black.

It seems to me that the values you entered match with the color you see. But I suspect you were give the wrong values somehow.

jlinkels
 
Old 10-08-2014, 08:58 AM   #3
Pedroski
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Ok, maybe what we see on the screen is not the same?? Or my son is colour blind? But his wife was there too!
 
Old 10-08-2014, 10:05 AM   #4
jlinkels
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I don't have the solution yet, but I created absolute colors quite often in the way you describe and try to do now. I used the Gimp colour picker to sample an on-screen image, and then used the RGB values in Inkscape. That is absolute color referencing and I can assure you they matched.

I think you son sees the correct color but uses the wrong dialog, or he has selected the wrong object. The quickest path could be that he creates a screen shot including the selcted object and the (docked) fill and stroke dialog. Even in the F&S dialog you can see which color is created if you look at the CMYK slider position. They all point at the selected color.

jlinkels

Last edited by jlinkels; 10-08-2014 at 10:12 AM.
 
Old 10-08-2014, 06:41 PM   #5
Pedroski
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Yeah, wierd. My son sent me the .svg file he made, 2 squares. One is filled with a grey-blue and one is a darker blue. The CMYK values are the ones I said for his idea of 'light blue'.

Anyway, thanks, I'll print a few then send to him. If he is not happy, he can tell me!
 
Old 10-08-2014, 08:36 PM   #6
sundialsvcs
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Remember that the device in question must be calibrated, and that you must be using the correct color-profiles for that device. (This is true for any operating system.) You can't just hold a color-meter up to a regular monitor and get an accurate reading. Not unless everything is calibrated and the device is built to do that.
 
Old 10-08-2014, 08:44 PM   #7
metaschima
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I'd say trust the numbers. People see colors differently and some degree of color blindness/deficiency is actually quite common. Different screens display colors differently unless meticulously calibrated.
 
  


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