[argyllcms] Re: Greenish cast in darker blacks

  • From: Pascal de Bruijn <pmjdebruijn@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 23 Dec 2009 21:26:39 +0100

On Wed, Dec 23, 2009 at 4:30 AM, Graeme Gill <graeme@xxxxxxxxxxxxx> wrote:
> Pascal de Bruijn wrote:
>> color cast. Since Firefox 3.5 doesn't use LCMS anymore, I'm guessing
>> this isn't a CMM issue.
> Possibly. Other explanations might be:
>  The white point is too different from the black point, and you
>  are noticing the transition from the neutral target to the black
>  point (ie. with the LCD default -k 0). Shifting the white target
>  to a hue nearer that of black may help, or using a -k > 0
>  may help at some cost to the contrast range.
>  It might be an optical effect (although your screen captures
>  hint otherwise). I've noticed some displays have quite
>  a hue shift with viewing angle near black, particularly
>  if the color is not naturally neutral. A larger -A parameter
>  may help in this situation (assuming -k 0).
>  It may be that the target curve shape is too much of a stretch
>  for the display near the dark end. This may be because the
>  current default is to use an input offset model of gamma curve
>  shape. You could try all output offset as an alternative (-f 1).
>  [I'm thinking of making this the default in 1.1.0 RC3].

Well, -f 1 seems to reduce the problem quite a bit... But it's not
completely gone...

The -A parameter did not really seem to make a difference at all.

Maybe I should try to create an XYZ LUT profile.

Pascal de Bruijn

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