[argyllcms] Re: Profiling in-camera color transformation

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sun, 16 Nov 2008 01:38:39 +1100

Pascal de Bruijn wrote:
I'm trying to create an ICC profile which imitates to color
transformation done by my camera.

I'm not sure what you mean by that. Do you mean you are
trying to profile your camera ?

So I photographed an IT8 target, in RAW+JPG mode. Then I developed the
raw with UFRaw,

Note that any "development" through a raw converted needs
to be kept constant for the profile to remain valid.

and converted to JPG to TIF with GIMP:

scanin -p -v -dipn -o IMG_4438_JPG.tif it8.cht

This merely gets the RGB values from the image. I'm
not sure why you are doing this given that the next command
does the same thing as part of assembling a .ti3 file.

scanin -p -v -dipn IMG_4438.tif it8.cht IMG_4438_JPG.val

This won't work. You need to provide the IT8 CIE reference values,
the values measured from your IT8 chart with an instrument either
by yourself, or provided by the manufacturer of the IT8 chart.

A profile provides a model of a devices color behaviour,
connecting the device values with the device independent
CIE standard observer values. For an input device this
means that two sets of information are needed for each patch,
one being the CIE values for the patch, and the other being
the device RGB values. scanin retrieves the latter from the raster file,
and combines them with the CIE values you have to provide. The RGB
values you have extracted from the raster file is not a source of
these values.

Graeme Gill.

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