Gamma

[glorybound]

An age-old question, but I don't think I know the answer. I have a donor scene, from the web, and the output gamma is set to 1. When would this be the correct way to go? I thought all should be set to 2.2.

[glorybound]

Nobody here?

[Streetwise]

I *think* the only time you'd go with the 2.2/1.0 setup is if your Color mapping is set to "Color mapping and gamma". Otherwise, as you know, 2.2/2.2 is standard these days and used with "Color mapping only (no gamma). Someone else chime in if I'm wrong.

btw - your screenshot suggests that the file is 2.2/2.2 but your system is already set to 2.2/1.0?

[glorybound]

Yeah, I accepted the files gamma, which set my system to it. I have since set it back to 2.2 across the board.

[glorybound]

I just purchased an HDRI (PG HDRI), with its own scene setup and again, the gamma out is 1.

[glorybound]

Also, I rendered the given scene (PG HDRI) and it looked fine. I deleted everything but the skydome and the camera, merged my model in and it rendered terribly. It was extremely dark. Then I merged the given scene's (PG HDRI) skydome and camera into my project scene, deleting my project scenes skydome and camera, and it rendered blown out. So confusing! This is what I get for trying to change things up a bit. I think I'll stay with what works. The given scene (PG HDRI) did have gamma out set to 1 and the burn value was something like .04. It is like the wild west when it comes to HDRI's.

[jackieteh]

I *think* the only time you'd go with the 2.2/1.0 setup is if your Color mapping is set to "Color mapping and gamma". Otherwise, as you know, 2.2/2.2 is standard these days and used with "Color mapping only (no gamma). Someone else chime in if I'm wrong.

btw - your screenshot suggests that the file is 2.2/2.2 but your system is already set to 2.2/1.0?

Yes, you are correct.

[glorybound]

Okay, but why would someone want that?

[Morbid Angel]

Bobby there is some confusion often associated with gamma correction. There are two different layers of gamma you have to account for. One is the input bitmap gamma. If you wish to work in srgb color space you need to gamma correct the input bitmaps so they don't look too washed out otherwise, so the 2.2 value is what it applies upon loading every bitmap before rendering. (this is actually a reverse value) since bitmaps are generally textures which are already in 2.2 gamma and need to be reversed to 0.4545 which then at render time is reversed back to 2.2. Second is the output bitmap. That one is strictly for 3ds max render output. If you don't use 3ds max render buffer and save from vray vfb then this field is ignored by vray. However for those who save from 3ds max buffer the output will either be gamma corrected to 2.2 or not depending on your setting.

As a general rule though you don't want to gamma correct float images like exr, hdr, 32 bit tiffs etc. If you use vray hdr loader it handles that automatically. So the gamma workflow is only needed for the 8 bit images.

With that said everything in rendering is happening on a linear curve meaning nothing is gamma corrected etc, and at the viewer (vray vfb) level the srgb or another curve is applied (so its not baked into the image) its why often people have an issue when they "see" image in vfb with srgb curve and it looks gamma corrected, then save it and it looks linear (dark).

[Vizioen]

Bobby there is some confusion often associated with gamma correction. There are two different layers of gamma you have to account for. One is the input bitmap gamma. If you wish to work in srgb color space you need to gamma correct the input bitmaps so they don't look too washed out otherwise, so the 2.2 value is what it applies upon loading every bitmap before rendering. (this is actually a reverse value) since bitmaps are generally textures which are already in 2.2 gamma and need to be reversed to 0.4545 which then at render time is reversed back to 2.2. Second is the output bitmap. That one is strictly for 3ds max render output. If you don't use 3ds max render buffer and save from vray vfb then this field is ignored by vray. However for those who save from 3ds max buffer the output will either be gamma corrected to 2.2 or not depending on your setting.

As a general rule though you don't want to gamma correct float images like exr, hdr, 32 bit tiffs etc. If you use vray hdr loader it handles that automatically. So the gamma workflow is only needed for the 8 bit images.

With that said everything in rendering is happening on a linear curve meaning nothing is gamma corrected etc, and at the viewer (vray vfb) level the srgb or another curve is applied (so its not baked into the image) its why often people have an issue when they "see" image in vfb with srgb curve and it looks gamma corrected, then save it and it looks linear (dark).

This should be stickied to avoid all future confusion for people that struggle with the gamma values.

[glorybound]

I guess since I always save in 32bit it isn't an issue for me. I am just surprised that most of the things I download from the web are set to gamma 1 out.

[^Lele^]

This should be stickied to avoid all future confusion for people that struggle with the gamma values.

We've done this for what, fifteen years now?

[Vizioen]

We've done this for what, fifteen years now?

Oh well would you look at that . I'm surprised people are still confused about the topic actually, it has been 15 years give or take, since this workflow.

[Morne]

We've done this for what, fifteen years now?

At least things got easier, since the days of your awesome VRay 1.5 LWF tuts, and the 0.2 for output on all bitmap textures!

[gagui]

Talking about this topic...
I miss an option in the new vfb for save the image with srgb color space baked in.
Right now if you save an image from the vfb which you are viewing with a srgb display correction it is saved in 2.2 gamma (or whatever you configured in 3dmax file gamma out preferences) wich is pretty close to srgb but not identical and some times that little loss of contrast is anoying.
What I do to get the image in srgb is copy (ctrl+c) the vfb content and paste it in photoshop and then save the image. Or save in .exr open it in a compositing software and save it as srgb. But all this is a bit anoying when you are look deving as you save a lot of tests...
Maybe I'm missing something and theres an easier way to do it...