[argyllcms] Re: Dispcal - Inverting Jacobian failed?

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 22 May 2009 10:23:31 +1000

Gerhard Fuernkranz wrote:


another though coming into my mind is do display an image with RGB patches

    [254,255,255] [255,254,255] [255,255,254]
    [253,255,255] [255,253,255] [255,255,253]
    [252,255,255] [255,252,255] [255,255,252]
    [251,255,255] [255,251,255] [255,255,251]
    etc.

on a white background. As long as no clipping occurs, the color of each
patch should differ from the white background surrounding the patch.
This would avoid the need to perform measurements; the test image can be
displayed statically and judged visually. The problem is however, I can
indeed measure a difference between e.g. RGB [254,255,255] and
[255,255,255], but my eyes cannot distinguish this difference - so the


One way of solving this might be a wedge with a superimposed visual texture
that modulates the wedge. The idea is that in saturation the
texture disappears. The texture might be a different shape for +ve and
-ve modulation, so that it's easier to see a change when one side
of the modulation is clipped.

cheers,
        Graeme.

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