Help with gamma and PS

[Gregow]

Hello,

I’m having some trouble figuring out how to get the best gamma curve, and getting things to work with Photoshop.

What I want is a good sRGB tone curve, so in DisplayCAL i’ve set the calibration to just that. No black output offset, no ambient light level adjusment (setting this based on ambient light measurments yielded a 2,8 gamma, which is far too high), and the default black point correction rate.

Black output offset set to zero.

CIE 1931 2 degree observer, 6500K whitepoint, white and black levels as measured.

XYZ LUT + matrix profile, without black point compensation.

Ran the auto-optimised test chart with 1134 patches, and medium calibration speed.

The result is, well…

In Photoshop it seems pretty OK, but I don’t think it’s recognising the generated profile. Otherwise the image looks washed out, more like a gamma 1.8 than 2.2.

Here’s a comparison with PS to the left and Windows image viewer to the right:

http://i67.tinypic.com/11kjwna.jpg

I actually think both of them are too light in the darks, but the right one is definitely worse.

Where am I going wrong with this, and how come Windows and PS are showing different results?

I’m using a ColorMunki Display to calibrate and profile an Eizo S2411W.

Any help would be appreciated.

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[Florian Höch]

In Photoshop it seems pretty OK, but I don’t think it’s recognising the generated profile.

If the profile is assigned to the monitor in Windows color management settings, PS will normally use the profile. I don’t think there’s anything wrong there.

more like a gamma 1.8 than 2.2.

sRGB is not gamma 2.2, just its average gamma is close to 2.2. But there are distinct differences to a 2.2 gamma in the shadows.

Where am I going wrong with this

I can see nothing wrong with your approach.

and how come Windows and PS are showing different results?

Photoshop uses the more accurate LUT, Windows photo viewer uses the less accurate matrix. It’s a shortcoming of the latter program. Personally, I use Picasa and XnView instead which have decent support for LUT monitor profiles via LittleCMS, and usually match PS visually.

[Gregow]

Thank you, seem like i’m at least on the right track with my approach. 🙂

After being away for a while and then returning to the computer, the profile actually looks to be excellent. There’s just less black crush and more detail in the darks, which threw me off at first. However, the tonality is actually excellent, with very good contrast.

So far so good, but… It doesn’t seem like the matrix profile is the reason for the difference. I generated a new profile with a swapped matrix, but things look the same.

However, I confused the Windows Image Viewer (which I never use) with the ‘Photos’, or whatever it’s called (on Windows 10). The Windows Image Viewer displays the swapped matrix, but the photo-viewer does not.

Now, I found something that made the photo-viewer (and Picasa) display the same as Photoshop, or vice versa (Photoshop now displays the same as the photo-viewer).

Under display adapter properties – color management – advanced there’s a greyed out check box, “Use Windows display calibration”. If you press the “change system defaults” button and go back to the advanced tab, the check box is no longer greyed out.

I saw some claim that if you check this Windows properly loads LUT-profiles. I have no idea if this is a valid claim, but it did make PS display the same as the photo-viewer.

Now, ironically, Microsoft Edge displays images the way PS used to… that’s a bit of a problem when putting things on the web…

Anyhow, the problem seems somehow related to how Windows handles colors. Unfortunately I have no idea how to set this up properly.

[Florian Höch]

but the photo-viewer does not.

Right, the Windows 10 Photo Viewer seems to be not color managed at all. MS has a way of breaking things in an unexpected fashion 🙁

I saw some claim that if you check this Windows properly loads LUT-profiles.

That’s correct, although unfortunately Windows quantizes the calibration to 8 bits (can introduce banding) and scales it wrongly, thus I normally recommend to use the DisplayCAL profile loader instead.

[Gregow]

I actually think MS is behaving properly. Thouhg it seems it needs a restart after changing profiles, if I want to load them with DisplayCAL loader (which I cerntainly do, now that you mentioned the quantization).

Here’s a comparison of Photoshop, Firefox and Windows 10:

http://i66.tinypic.com/dnzofo.jpg

Photoshop and Win look the same, but Firefox is a bit off.

Firefox looks the same as if I would reset the videocard gamma table.

Could it be that Firefox uses the generic sRGB profile as my display device profile?

[Florian Höch]

Could it be that Firefox uses the generic sRGB profile as my display device profile?

For Firefox, you may have to go to about:config and set gfx.color_management.enablev4 to true  and restart the browser. Note that Firefox does not have multi-monitor profile support (not sure if this affects you).

[Gregow]

Yes, that’s what i’ve done. Firefox also recognises ICCv2 and ICCv4 tags, but the device profile doesn’t seem to work (looks just like in Microsoft Edge).

It’s only a single monitor setup. 🙂

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