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Linear workflow headache with photoshop

YaricYaric0 Posts: 0Member
Okay, so I've always had at least a basic understanding of Gamma correction and linear work flow. Lately I've been working really hard on understand it more and applying that understand... Anyways, I'm in 3d max say, and I'm using Vray. I've got 3dmax working in linear workspace obviously and I'm having Vray output 1.0 Gamma. If I save that final render out as a 32bit HDRI then open it up in photoshop CS2... Photoshop appears to be applying gamma 2.2 automatically. I've confirmed this by reading this following site.

http://www.mintviz.com/articles/gamma-correction-and-linear-workflow-explained/

My question is why does photoshop do this? And how are you supposed to utitlize a linear workflow in gamma 1.0 in photoshop if it is automatically adjusting it to 2.2? If you open up the adobe bridge browser it is showing the thumbnails with the proper 1.0 gamma, just when you open them it's 2.2. Also, if you save out say an EXR file at 32 bit it does the same thing, along with TIFFs, however, if you save at 8 bit it doesn't automatically change the display gamma to 2.2.

There are so many opinions and tutorials online it took me forever to figure out this is what was happening. Alot of people were saying to render at 2.2 and save out as HDRI. However, when you do that and open it up in photoshop, it's making the gamma 2.2 X 2 making it very washed out. That killed my brain all last night until I found that link I pasted up there about PS automatically adjusting it.

Anyways, any help is appreciated.

Thanks!
Post edited by Yaric on
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  • IRMLIRML176 Posts: 0Member
    this is because a HDR image should always be 1.0 gamma when saved, and a LDR image should be at display gamma 2.2, so photoshop is adjusting the HDR image to also be display gamma

    I still use photoshop 7 so I don't know if there are any settings for you, but you can always do it manually by adjusting the gamma of the image yourself after you import it to photoshop, if you set the gamma to be 0.4545 that will turn the 2.2 image into 1.0, and you can work on it that way

    I do all my HDR work in after effects, which lets me set display gamma and render gamma and gamma for all my different elements individually, a good program should let you modify the gamma of elements when you import them, I would be suprised if photoshop couldn't do this

    also check that photoshop isn't just setting a display gamma which is confusing you into thinking it's changing the gamma when it's just simulating the correct display
  • YaricYaric0 Posts: 0Member
    IRML wrote: »
    this is because a HDR image should always be 1.0 gamma when saved, and a LDR image should be at display gamma 2.2, so photoshop is adjusting the HDR image to also be display gamma

    I still use photoshop 7 so I don't know if there are any settings for you, but you can always do it manually by adjusting the gamma of the image yourself after you import it to photoshop, if you set the gamma to be 0.4545 that will turn the 2.2 image into 1.0, and you can work on it that way

    I do all my HDR work in after effects, which lets me set display gamma and render gamma and gamma for all my different elements individually, a good program should let you modify the gamma of elements when you import them, I would be suprised if photoshop couldn't do this

    also check that photoshop isn't just setting a display gamma which is confusing you into thinking it's changing the gamma when it's just simulating the correct display

    Yeah, I'm thinking after effects may be superior in it's handling of gammas/workspace. I watched a video on youtube with a guy demonstrating how after effects handles workspace. You would think photoshop would be similar but it doesn't appear to. I've looked though the help and all over google and haven't found anything similar or equivalent to after effects in it.

    Anyways... one thing I have been confused about lately is when people say to adjust the gamma in there photoshop. When you go image>adjustments>exposure you get exposure and gamma control. If I change the gamma setting to where it says 2.2 from 1.0 the image gets darker. I don't get that, it's like the controls are inverse. It seems like when you increase the gamma the picture should be corrected upwards, but it doesn't. When you do that to 2.2, press okay, then go back and adjust it to .454 you're back where you started in terms of brightness. :confused: So basically making those gamma settings lower makes the image brighter...

    Edit: actually, I did find something here... under edit>color settings you can specify your workspace. Hmm....
  • japetusjapetus178 Posts: 744Member
    What version of photoshop are you using? I haven't had problems with color display in CS5. I have had some problems with alpha fringing, but in CS5, 32bit support is much improved over previous releases. The problem I have now is that Bridge actually does NOT display my .exrs in the proper gamma. So I seem to have the reverse problem.
  • japetusjapetus178 Posts: 744Member
    I noticed you found the workspace color settings. Mine is set to sRGB IEC61966-2.1 and I don't have gamma issues. Maybe check that?
  • YaricYaric0 Posts: 0Member
    japetus wrote: »
    I noticed you found the workspace color settings. Mine is set to sRGB IEC61966-2.1 and I don't have gamma issues. Maybe check that?

    I have CS2. I've found out that if you go up to view and click on proof setup and click on monitor RBG, then go and click on proof colors it'll display the proper gamma. The workspace settings under color settings don't really seem to do anything for me. I'm probably just too dense to understand it :(

    And yeah, that's weird about your bridge viewer. Mine seems to display the proper gammas there.
  • japetusjapetus178 Posts: 744Member
    Ah, well that could be your problem too! Glad that you fixed it, very annoying! Adobe products boggle the mind sometimes.
  • DjuinDjuin0 Posts: 0Member
    Ok I think I have some of this. . . First I'm way still learning these programs, so take what I have as you would a small child who thinks the moon overhead follows him home night ^_^, anyway. . . The whole thing about inverse gama with the image>adjustment>exposure stuff, I may not be correct but it seems to me that when you use an art program, so far it seems any, and adjust the gama through it, you are adjusting it for other displays, not your own. The reason it gets darker is because when viewed on say google chrome at your local library, these probably lack luster displays (as I think are most actually) natively are set to a corrected gama of 2.2, so to them the adjusted image looks as intended? . ? . If they were to view a 1.0 gama image wouldn't it look way to dark, is that the difference in changing your screens gama persay, and "adjusting" for a display, Yes? (like setting a smaller record to a higher speed so it sounds normal? you know . . .45's, I can't be that old ^_^

    Anyway my larger point is, isn't it really about how your client/audience will view it, and not necessarily you? Like I said I could be way off base, I'm just trying to make sense of it all too. If I am wrong I hope at least these are new links to yall ^_^

    This is an amazing bit of info I found about adjusting max and v-ray, with follow along photos, and whys, and hows . . . http://renderstuff.com/using-gamma-2-2-cg-tutorial/
    and a great just general in depth look at gama . . . http://www.breidt.net/scripts/gamma_correct_v12.pdf

    Hope my first post was an ok one, HI everyone!!!

    EDIT: Oh ya great, OP! And great info on using After Effects, thanks guys!
  • IRMLIRML176 Posts: 0Member
    I think maybe you are a bit confused, it's always hard to tell what people really mean when talking about gamma because there are lots of confusing terms

    displays are at 2.2 gamma (maybe some vfx studios have linear monitors, I don't know, but it doesn't matter here), you don't change your display, you render at 1.0 just to get the benefits of correct colour blending, then you change the render back to 2.2 again so it can be viewed correctly on a display
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