Re: Lab color is in or out of gamut
Re: Lab color is in or out of gamut
- Subject: Re: Lab color is in or out of gamut
- From: Roger Breton <email@hidden>
- Date: Thu, 25 Jul 2002 08:05:43 -0400
Le 7/24/02 1:06 AM, + email@hidden ;
<email@hidden> a icrit :
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Message: 1
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Reply-To: "publix team" <email@hidden>
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From: "publix team" <email@hidden>
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To: <email@hidden>
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Subject: Lab color is in or out of gamut
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Date: Tue, 23 Jul 2002 09:21:30 +0200
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Hi Group,
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is there an easier was to check if a Lab color is in
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gamut than using the gamut warning in photoshop ?
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-Daniel
Daniel,
You could use a graphical pencil and paper approach. Draw a grid on some
paper. Let the horizontal axis be the a* and b* and the vertical axis the
Lightness (L*). Now, you will need two sets of grids: one for the +a to -a
axis and the other to plot the +b to -b axis. Two separate sheets.
Next, open up an IT8.7/3 CMYK image (the Basic 182 patches will suffice to
begin) in Photoshop to which you assign the CMYK profile you want to study
the gamut. Set the RI to AbsCol in Color Settings.
Simply read in the Lab values of each CMYK patch with the Color Picker. And
plot the corresponding points on one of your two grids. After plotting
enough points, you'll start to see a pattern emerge.
Finally, to check whether a Lab color is in gamut, simply try to plot it on
one of your two graphs. If the color plots outside of the clouds of points
you've already plotted above then you know it is not in gamut.
Best of luck.
Roger Breton
Laval Qc
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