Shadow Blocking in Photoshop when using monitor profile

FG
Posted By
Fabian_Gonzales
May 12, 2005
Views
350
Replies
11
Status
Closed
Hi,

I own a Mitsubishi DiamondPro 930SB 19" monitor (same as the NEC 912SB), which has a special sRGB mode, and comes with an ICC monitor profile, which I installed as the default monitor profile in Windows XP.

This works great, and I get very accurate results from it, except that in Photoshop, this profile causes the shadows to block up and amplifies shadow noise.

The strange this is that the profile works perfectly in other color management-aware applications, including Nikon Capture and Capture One PRO (both of which deliver excellent – and identical – results).

I’ve tried using the Microsoft engine instead of the Photoshop one, and turning off/on the black point compensation, but to no avail.

Any ideas? This problem occurs on both CS and CS2, which I recently installed a 30-day trial version of.
Related Tags
monitor profile shadow

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CC
Chris_Cox
May 13, 2005
No idea – Photoshop is just using the data in the profile…
FG
Fabian_Gonzales
May 13, 2005
I just did some more testing, and found out that Adobe Gamma refuses to load my monitor profile as a base (claims it’s not a valid monitor profile). Windows XP loads it just fine, and when I looked at it using the ICC Profile Inspector it reports the type as "display". Everything looks normal – I cannot find anything wrong with it.
CC
Chris_Cox
May 13, 2005
Adobe Gamma only accepts matrix/TRC profiles – your profile could be an LUT profile. But if you’re using an sRGB profile, that shouldn’t be an LUT profile.

My guess is that there is something odd about the profile.
FG
Fabian_Gonzales
May 20, 2005
Could it be a precision or rounding error, since this only happens at very low RGB values? (Again, the shadow blocking only happens in Photoshop – other applications are fine.) I have permission from NEC to forward the ICC profile to you. Would you like to have a look at it?
CC
Chris_Cox
May 21, 2005
I don’t know — the color conversion engine in Photoshop shouldn’t have any problem with precision (and I increased the precision of the display pipeline in CS2).

Yes, email the profile to ccox at adobe dot com.
SK
Stefan_Klein
May 21, 2005
Chris,
"and I increased the precision of the display pipeline in CS2" Could that be the reason why redrawing takes longer than in CS1? Is CS2 now able to handle LUT monitor profiles better than previous versions? Stefan
CC
Chris_Cox
May 24, 2005
Photoshop has always handled LUT profiles well (assuming the profiles were built correctly).

And yes, the changes account for some drawing slowdown.
But problems with video card drivers are causing bigger problems.
JC
Jay_Craig
May 24, 2005
FWIW, I’m getting a similar message on trying to load my eye-one display profile into Adobe Gamma’s control panel.. ie. not a legal profile I think was the terminology.

Does one really have to load a monitor profile into Adobe Gamma, as the profile seems to kick in on startup in windows?
CC
Chris_Cox
May 24, 2005
If you’re using Eye-one to calibrate, then you should REMOVE the Adobe Gamma Loader and use the Eye-one loader instead (as explained in the eye-one manual).
JC
Jay_Craig
May 24, 2005
I have the EyeOne loader and have removed the Adobe loader from start menus. I was also confused though by this Adobe technical document that indicates that even if you do this, its still recommended to load the 3rd party profile into Adobe Gamma?

<http://www.adobe.com/support/techdocs/321608.html>
CC
Chris_Cox
May 24, 2005
That only applies if your software doesn’t set the correct registry entries to tell the OS (and applications) which profile belongs to the display.

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