Weird Gamma Issue

[rusteberg]

I'm getting a weird gamma issue with 3.2003 - Max 2012. Sometimes the gamma drops out within the frame buffer as well. Doesn't matter if I overide the default gamma values when saving to jpg, tif, or png. Saving to floating point .exr saves as expected (same as vfb) I even tried loading ICC to see if it need that, but it still saves out differently. Sooooo I'm a bit baffled here.

[Deflaminis]

Hmmm. My guess is that your photoshop is loading profiles incorrectly. I've had problems here in the past.

Does it look the same in windows image viewer? how about a web browser? Email?

If it looks fine there but not in photoshop, it's a profile problem. This page can be helpful, but ugly. http://www.gballard.net/psd/colorlooksbad.html

[rusteberg]

No, it's not a photoshop issue, nor any other image viewing application issue. It's an issue with the vray frame buffer not saving out what it's told to

It seems to be tied to the "quick" vray settings panel - I thought I made that clear with the initial attachment, but I guess since I only have a handful of posts here nobody thinks I know what I'm doing...... Is an essay with footnotes required?

[tashko.zashev]

Hi,

The screenshot attached shows that the Output Gamma is set to 1 and most probably this is the reason why the saved image files are with different gamma compared to the V-Ray VFB. Setting it to 2.2 should give you exactly the same image on both screens.
Our VFB shows the final render image in sRGB space - "Display colors in sRGB space" is "On" by default.

[Deflaminis]

Photoshop uses different profiles based on what bit depth you rendered to, so it wasn't out of the question. That explains why your exrs work and your others didn't, but overriding to 2.2 is probably it, as suggested. Best of luck.

[rusteberg]

Hi,

The screenshot attached shows that the Output Gamma is set to 1 and most probably this is the reason why the saved image files are with different gamma compared to the V-Ray VFB. Setting it to 2.2 should give you exactly the same image on both screens.
Our VFB shows the final render image in sRGB space - "Display colors in sRGB space" is "On" by default.

I anticipated that and still find the output not to line up when saving below floating point..... Here's an example:

[tashko.zashev]

I anticipated that and still find the output not to line up when saving below floating point..... Here's an example:

I believe this small difference is due to the sRGB color space applied to the image in VFB. The sRGB curve is slightly different then the Gamma 2.2 one and such difference in the image are expected to be visible.
The best way to compare both images is to save EXR 32bit file and open it in Nuke or any other software that has support for sRGB profile.
Another approach is to disable the sRGB from the VFB and change the 3DS Max Gamma output to 1 and they will look the same again.

Please make a test and let me know if you still have problems to get identical results.

[rusteberg]

I can't figure out why when I render with the solidrocks plugin I get what I see in the vfb, but when I manually go through vray from scratch or through the quick settings I get discrepancies....




Vray settings - frame buffer vs. output (system default gamma)






Vray settings - frame buffer vs. output (override system gamma 2.2)






Solidrocks - frame buffer vs. output (system default gamma)

[tashko.zashev]

I just sew that we posted at same time.

However, the first image shows the difference between the gamma 1 and sRGB.
The second one shows the difference between the Gamma 2.2 and sRGB curves.
Actually I'm not sure what is the setup for the third one. I have to check the Solidrocks settings.

Would it be possible to attach one of your Max scene file, probably the scene with the teapot, just to be sure that everything is set correct?

[rusteberg]

Hi Tashko, sorry for the slow response here's a basic scene that saves out weird as mentioned above: TEAPOT SCENE

[tashko.zashev]

Hi Tashko, sorry for the slow response here's a basic scene that saves out weird as mentioned above: TEAPOT SCENE

Thank you.

Actually I don't see any problems with the settings in this scene. Normally when saving 8bit images from the VFB you have to manually set the Gamma output value in 3DS Max 2012 in order to get a file with baked 2.2 gamma. Otherwise the resulting file will be darker than the VFB preview where sRGB curve is applied to the rendered image by default.