[argyllcms] Re: Perceptual intent in Display profiles?

  • From: Michel Joly de Lotbinière <michel@xxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 25 Nov 2009 01:47:10 -0500

O.K., I've tried the -aS and -aG options to colprof, using the
original large measurements file for the original calibration. The
result with colprof -aS -qh is good: the darkest discernible textures
correspond to RGB numbers around (10,10,10) and above in the file. And
greys remain grey--well, there's just a slightest hint toward the warm
side, only observable on large areas of the darkest greys surrounded
by pitch black, e.g. black bears cavorting on moonless nights,
something only the most dedicated pixel-peepers photograph.

And the brightest 5-7 RGB levels actually do show very slight
discernible differences from white, which the LUT profile did not.
Great for noticing blown highlights.

Profile testing does show larger errors than a LUT profile, but the
difference isn't really visible.

On Mon, Nov 23, 2009 at 7:04 PM, Gerhard Fuernkranz <nospam456@xxxxxx> wrote:
> Michel Joly de Lotbiničre wrote:
>> [...] (matrix profiles were not good on the neutral grayscale quality 
>> measure) [...]
> Did you use the -as/-ag or the -aS/-aG options? The latter create equal
> shapers for the R, G and B channels, avoiding that the profile can ruin
> the good neutral gray axis again that was established by the calibration.
> Regards,
> Gerhard

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