Gamma correction - do you care?

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View Poll Results: Do you have a linear workflow and gamma corrected output?
I have a fully linear workflow and everything under tight control. 282 32.49%
I understand gamma correction/linear rendering but it's too much hassle. 146 16.82%
My clients/boss/coworkers/tools don't care so why should I? 48 5.53%
I read about it but never quite understood that topic. 289 33.29%
What are you talking about anyway? 103 11.87%
Voters: 868. You may not vote on this poll

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Old 03 March 2008   #1
Gamma correction - do you care?

Since dealing with it at work, I'm noticing that there is quite some confusion about the why and how of gamma correction and linear rendering, that is if people even know that it exists.

So I'm wondering about how do others deal with it? Do you have a linear workflow? Do you know about and ignore it because it's just easier to not bother? Or did you never see the necessity to find out what the 'gamma' thing in the render settings does?
 
Old 03 March 2008   #2
I think it would stand to reason that anyone working professionally creating CG imagery would know about such things.
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Old 03 March 2008   #3
I would have thought so too, but I was surprise to find many people around me who made their living in CG and did not know. Heck, how come so many commercial 2D imaging applications run all their filters in gamma space instead of linear space (see this for example)?
 
Old 03 March 2008   #4
Originally Posted by leigh: I think it would stand to reason that anyone working professionally creating CG imagery would know about such things.


My experience is that almost no one outside of high-end film has more than a inkling of how it works... in 18 months working in production, I've yet to have any colleagues, contractors, or clients (cg artists themselves) have a grasp of it, and the typical attitude is not to worry about it.

I'd very much like to understand it more, but no one around me gets it and I haven't found much clear literature on the subject.
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Old 03 March 2008   #5
you miss a category:

I use linear workflow as I seem to understand it but I am not quite sure about the right way and the result I should get.

That right, Since I use LWF I find my output to be a little washed out.
 
Old 03 March 2008   #6
Originally Posted by JDex: My experience is that almost no one outside of high-end film has more than a inkling of how it works... in 18 months working in production, I've yet to have any colleagues, contractors, or clients (cg artists themselves) have a grasp of it, and the typical attitude is not to worry about it.

I'd very much like to understand it more, but no one around me gets it and I haven't found much clear literature on the subject.


I don't think there's *that* many people even in high-end film who really understand it either. I was incredibly resistant to it at first because of the exta complication it involves, but the results really are worth it.

However it's actually quite difficult to convince other people that it's right. People are so used to looking at images for years in a non-linear space that intuitively it doesn't feel right to them. Then there's some really weird stuff to do with the non-linear response of the human eye too that confuses the hell out of many people.

Haven't really got to grips with log and scanning and print lights and all that jazz yet either... I'm waiting for the fully digital pipeline to come around so I don't have to!
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Old 03 March 2008   #7
I did a tutorial for Blender users about it, I use it and it is common to have such feature in last generation render engines. Although linear workflow means that the display device should be calibrated and for beginners this is a first step to take and understand before ever considering the linear workflow thing.

http://forums.cgsociety.org/showthread.php?t=305727


I have a question about the linear workflow:

Should light colors and background colors back corrected to linear space in the render engine before rendering?
 
Old 03 March 2008   #8
I've met more people than I'd ever thought possible in the high end film industry who have no freaken clue whatsoever about deep shadow maps, different colour spaces, response and timing issues and a million other things, and yet they deal with it everyday (and often force someone else downstream to fix their shit).

I'd say the people aware of what they are doing to an extent higher than that of your average chimp don't make more than 20% of the film industry.
Gamma and linear rendering might make that slice even smaller.
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Old 03 March 2008   #9
So how can we get over this hump as an industry... maybe this would be a good topic for a CGWorkshop (series?!?). I'm taking a course at fxPHd on digital color theory, and it's a good class, but it hardly takes the dust off of the surface, forget scratching the surface.

I'll check out that blender tutorial... didn't know about that one. Thanks!
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Old 03 March 2008   #10
Talking

Originally Posted by JDex: So how can we get over this hump as an industry... maybe this would be a good topic for a CGWorkshop (series?!?). I'm taking a course at fxPHd on digital color theory, and it's a good class, but it hardly takes the dust off of the surface, forget scratching the surface.


I actually teach a masterclass at siggraph that will touch on the topic. It wasn't planned to be the main topic but....

/Z
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Old 03 March 2008   #11
If I can make LA this year, I'll find a way to that class... I'd hate to put this as the main topic when there's so much else you could share Zap, but I'm sure there's an audience for a full-dose of gamma control.
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Old 03 March 2008   #12
Sooooo as someone who is eeking out whatever knowledge they can about 3D while hoping to become more involved in the industry as his education progresses - where does one learn about Gamma and Linear Rendering?

I did look up gamma and found a number of references to how your work appears on the monitor. Is that the same type of gamma that you're referring to?

http://www.cgsd.com/papers/gamma_intro.html

As far as Linear Rendering I found this :

http://highend3d.com/3dsmax/tutoria...g/vray/147.html

So my understanding after reading these pages is that when you create an image, your monitor will by default darken the image. Gamma is a setting then used to counter balance that effect by bringing up the image and, specifically, the shadows?

I have found how to enable Gamma in my renderer (MentalRay) but am not sure how to decide what is an acceptable value? Is it determined by your eye, or is there a formula to use? Or an acceptable range? Or a tool to test your monitor so you know how to balance?

This is then linear rendering?

Thanks or the thread, interesting stuff.
 
Old 03 March 2008   #13
A monitor will, by default, darken the image, so images have to be gamma-corrected (made brighter and less contrasty) in order to display properly, either in the display program, or by baking into the render (most renderers allow you to do this).

This means that if you're painting a texture, you're unconcsciously painting it non-linear because of the way the monitor's presenting it to you.

So you have to apply an inverse-gamma correction to re-linearize the data before passing it to the renderer, as a renderer expects everything to be linear or the maths doesn't work.

The same is true of plates for compositing.
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Last edited by playmesumch00ns : 03 March 2008 at 05:55 PM.
 
Old 03 March 2008   #14
Originally Posted by JDex: So how can we get over this hump as an industry...


We get over it by hiding as much of this crap from your average TD as possible Seems to be working pretty well these days
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Old 03 March 2008   #15
Originally Posted by playmesumch00ns: A monitor will, by default, darken the image, so images have to be gamma-corrected (made brighter and less contrasty) in order to display properly, either in the display program, or by baking into the render (most renderers allow you to do this).

This means that if you're painting a texture, you're unconcsciously painting it non-linear because of the way the monitor's presenting it to you.

So you have to apply an inverse-gamma correction to re-linearize the data before passing it to the renderer, as a renderer expects everything to be linear or the maths doesn't work.

The same is true of plates for compositing.


I have been looking around in Photoshop, I can't seem to find an inverse gamme correction plugin anywhere. Could it go by another name? I found some gamma tutorials on-line which mess with the levels, is that where I should be looking?

Don't all monitors have different levels of darkness that need to be corrected? I noticed at work and home one of my 3D renderings look really good, but when I take them in to school to show the prof they appear super dark. So do I eyeball what gamma correction looks good, or is there a rule of thumb?
 
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