Photoshop softproof and gamut warning

[DaveRichardson]

Hi guys I hope someone can help me. I raised this issue on the Adobe forums but have had no reply so far.

In CS5, when I have a softproof selected (using Relative Colormetric ; Blackpoint Compensation and Simulated paper color)  I am seeing a difference in the soft proof when I toggle the gamut warning on and off.

This is not due to the highlighting of out of gamut colors which I have set to show up as a 100% medium gray.

What I am seeing is a difference in the shadow detail in the on screen softproof, when I switch the gamut warning on or off. More detail with it off and less with it on. 
This was using my own printer profiles - however I tried canned profiles and saw the same effect.

I had not noticed this before, but yesterday I was printing some sunset pictures which had lots of shadow in the foreground. I was having trouble getting the shadow detail to match between the on screen softproof and the print. The rest of the picture was a good match. My expectation of toggling the gamut warning is that it would only highlight (in medium gray) the out of gamut colors and have no impact on other parts of the picture.

Incidentaly - the view with gamut warning "on" appears to match the print correctly.

I am using CS5 on Windows 32bit.

Has anyone else seen this or am I doing something wrong ( or have I misunderstood the gamut warning)?

Thanks  Dave.

 

[digitaldog]

What I am seeing is a difference in the shadow detail in the on screen softproof, when I switch the gamut warning on or off. More detail with it off and less with it on. 

I’ve never seen that. I don’t use the gamut warning but none the less, it should not affect the soft proof itself. All images? All profiles? Any possibility you can try this on a different system?

[DaveRichardson]

Thanks for the quick reply.

I've tried it on a range of images. To be honest I had never noticed it before (and have been using CS5 for quite a while) - but it seems to effect the extreme shadow detail ( brightness less than 10%) which may be why it came out on the sunset pictures I was printing. I therefore pulled out some night pictures and I can clearly see the softproof change when switching the gamut warning on and off.

I tried different printer profiles, and different rendering intents - but I see the same effect.

I only have photoshop on one system - but will try on a friends system at the weekend.

Dave

[DaveRichardson]

After a bit more experimentation, I find that this problem disappears if I disable Open GL but re-appears if I enable it.

It still seems strange to me that there is any impact on the display of the softproof just by toggling  the Gamut warning.

Dave

[DaveRichardson]

For the benefit of anyone else experiencing the same issue :

A problem has been highlighted on the Adobe forums, which Adobe are investigating, with slight banding appearing on screen when using Open GL in Normal or advanced modes. It would appear that switching the Gamut warning on and off when softproofing also impacted the banding (I tried it on a gray ramp and could see the banding in the dark gray areas that I had problems with in my original post).


The work around, until Adobe get to the root of the problem, to use Open GL "Basic" mode.

This work around resolved my problem.

Dave