RE: Finding CIELab Values from Target Chart TIF
RE: Finding CIELab Values from Target Chart TIF
- Subject: RE: Finding CIELab Values from Target Chart TIF
- From: Roger Breton <email@hidden>
- Date: Wed, 28 Apr 2010 22:42:55 -0400
Joseph,
May I ask what makes you think that this TIFF file as an absolute set of
"Reference CIELab values"? I could be wrong but, to my knowledge, these
charts never have an a-priori set of associated CIELab values.
Best / Roger
>
> > Dear List
> >
> > I have a 140 Patch Target TIF file that I don't have access to the
> > Reference CIELab values.
> > The chart is used by PhaserMatch 4.0 (created by X-Rite for Xerox).
> >
> > Requests to both Xerox and X-Rite have not been fruitful and so I'm
> > now wondering if their is a way to "extract" these values from the chart
> itself.
> >
> > I have opened the the Chart TIF in Photoshop and can read the L*a*b*
> > values in the Info palette - but only as single digit L*a*b* values.
> > Is there a method to obtain more precise (minimum 3 decimal places)?
>
>
> The Lab values you are seeing in photoshop are just a simulation. They are
> calculated from the RGB / CMYK values in the tiff file using your current
> colour settings. This is assuming that the TIFF file is not an Lab file.
> If you wish to have more precision, use photoshop or any other image
> viewing software to extract the RGB/CMYK values for the patches. You can
> then use Colorsync utility or any other such tool to extract more precise
Lab
> values using CMYK/RGB profiles for the process you are trying to simulate.
>
>
> Peter Skarpetis
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