[argyllcms] Re: Posterization caused by profiles

  • From: william.wood@xxxxxxx
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sun, 10 Dec 2006 21:01:35 -0500

argyllcms-bounce@xxxxxxxxxxxxx wrote on 12/10/2006 07:52:55 PM:

> So what to one person can be a good trade-off ("I got
> a really bright, colorful result and lost a little shadow
> detail", can be terrible to someone else ("I lost all
> my shadow detail").

I'm concerned that the leaf in the center has lost all detail.

> The "with profile applied" image has a strong degree of
> saturation and contrast enhancement, and this is often
> indicative of linking a large gamut colorspace to a
> small gamut destination without proper gamut mapping.

I'm not familiar with specifying the gamut mapping.  Are you saying I
should specify that the profile is to be used only with, say, images that
are in the sRGB space?

I've never had to do this with Monaco OptixPro software, and it doesn't
produce the posterization so I was surprised to see posterization in
Argyll.  I tried creating the profile again with -qh and it improved
somewhat; I'm tempted to try -qu now ;-)

> It's not possible to say more without knowing:
>    How your profile was created.

profile -v -A "Lenovo" -M "T60" -D "T60 IPS" T42pk1f500

>    What intent tables were built.

Don't know - can you tell by the commad line?

>    What source gamut the tables were created for.

Don't know - must you specifiy this?  I thought that was an optimization
only, that you could still get a good profile without limiting it to one
source profile?

>    What source profile it was linked to.


>    What intent was used in the linking.


>    What type of linking was used (ie. active or passive linking).

Using MS or Adobe color engine - are they passive?  I don't know for sure
what the difference is.

> [A device profile doesn't transform colors on its own -
>   this only happens when it's linked with another device profile.]


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