2011 - Color Management for LWF ?

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  04 April 2010
Sorry, I missed that you already said that it is washed in render view.
I just downloaded your scene, open it, hit render and it looks OK in render view.
Also when preview batch rendered image in PS it looks OK there too...
 
  04 April 2010
Jason I downloaded you scene and it works fine here, nothing washed out. I don't know what's up. Have you set your renderview to 32 bit and restarted?


For everyone else. There is a lot of confusion in this thread - some good advice and some bad advice. The simple version:

Turn on colour management. Change your renderview input image profile from sRGB to Linear.

That's it.


Do not use gamma nodes. Do not use lens shaders or tonemappers. Do not tweak the Framebuffer Gamma setting. If you want to use Maya's colour management features all of those things are unnecessary, and in most cases will break all the hard work you put in following the steps above.

Now for the problems/bugs and workarounds...

If you need to use physical sun & sky locate your mia_exposure_simple shader and get rid of it. (You'll also now need to adjust the gain on the mia_sky node from 1 to 0.2 because by default the mia_sky/sun are very bright and the exposure node usually compensates with a gain of 0.2). IMO this is a developer oversight and Maya should no longer automatically add that lens shader. Once you understand why you don't need it, you might discover a reason for keeping it, but for now, delete it.

Procedural textures are always linear, so despite what I said above, you may want to dig out the old gamma nodes if you're using procedurals for colours maps etc. It's a shame, but we're holding out for a fix.

Colours entered into colour swatches in your shaders or lights are also linear whereas you'll be 'thinking' in sRGB. So you'll need to compensate somehow, either by gamma correcting in your head, in a calculator, by pure guesswork or by piping a single colour ramp texture through a gamma node. This is even more of a shame, but don't worry the AD guys are already fully informed on how lame this is.

If you need to use image planes you need to know that Maya assumes all image planes are linear and you cannot tell it otherwise. Your best bet is to linearise the image in a 2D app before bringing it into Maya. Depending on the app this process entails gamma correcting by 2.2 or .454. The resulting image will look dark in your 2D app and in Maya. Now if you use the colourpicker to pick colours from the image plane you'll be selecting 'correct' colours - linear image -> linear image plane -> linear colour picker -> linear swatch -> linear procedural/light. All good. And when you render the image your image plane will look correct.

If you want to use PSD textures, again Maya assumes they are linear and does not give you an option to change it. You'll need to create a colour profile node, set the profile to sRGB then via the connection editor connect the colorProfileType of that node to the colourProfile of the PSD node. Henceforth Maya will know your PSD is sRGB and you won't need a gamma node.

The same as above applies to the 'movie' 2D texture node.

If you want to use an IBL node, again Maya assumes it's linear. Given that you'll most likely be using an HDR, it's best that your image is linear anyway.

Sounds messy but IMO it improves on both of the existing linear workflows considerably, has less bugs (cgbeige rants notwithstanding), and is well designed for future expansion.

Hope it helps.


Edit: wherever I say "Maya assumes xxx is linear" what I really should say is that Maya does not perform any colour management on xxx so if you're rendering linear, xxx is treated as if it's also linear.
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Last edited by mattwood : 04 April 2010 at 11:22 PM.
 
  04 April 2010
Thanks, mattewood, those suggestions and workarounds are really helpful.

I finally got a non-washed-out render after deleting the whole Maya 2011 preferences and using a new default preference. Guess there is something to do with inheriting preferences from Maya 2010.

Still, there is difference between the result generated under Maya 2011's CM system and old style gamma node linear workflow approach.

Here is the Maya 2011 CM Enabled batch render result viewed in Nuke:


As a validatin, here is the Maya 2011 CM Disabled with a gamma correct node (0.455) placed between color texture and materials. Batch render result viewed in Nuke: (looks exactly the same as the one I got from Maya 2010 using the same method)


The difference is:


You mentioned the light color has to be considered as part of the linear workflow. I agree, but I don't think I should gamma correct my pure white directional light's color with 0.455 as it will obviously too dark in this case.

So, what's causing the difference? I thought in Maya 2011's, when sRGB is specified as Default Input Profile (CM enabled), it is equal to a gamma correct node (0.455) applied to color textures?

RagingBull, you can save time uploading the scene.

cheers,
Jason
 
  04 April 2010
Jason, as far as I can tell your settings are correct and maya 2011 has some problems with their new color management.
I agree with the previous poster that this thread contains some incorrect statements - so many in fact that it would be difficult to address each one, so I'm just going to state what I believe is wrong with the new color management based on a simple test (like Jason's) with a JPG fileTexture being rendered to a EXR format with a 32-bit frame buffer which is viewed in the renderview window.

I think the correct settings should be:

Render Settings:
Enable Color Management
Default Input Profile = sRGB
Default Output Profile = Linear

JPG fileTexture Attributes:
Color Profile = Use Default Input Profile

RenderView Display Color Management (defaultViewColorManager) :
Image Color Profile = Linear
Display Color Profile = sRGB

My scene has no lights, no default lights and uses a surface shader. Result is washed out when I compare to original JPG. (About the same amount as your latest test Jason - not as much as your first one).

I discovered that if I set Display Color Profile = Rec. 709 then the result looks correct. Now the render view displays the same as the original JPG. This is a mistake in the color management since my monitor is sRGB

You may think this is ok, and just set it to rec709, but the other problem is that the resulting EXR is not correct either. I found that I needed to add a gamma 0.8 in photoshop to make it correct (by eye). Strangely this is the inverse of 1.2 which got me thinking... did some programmer just mistype the gamma value? Hmmmm.

good luck sorting this out

David
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Last edited by djx : 04 April 2010 at 02:52 PM.
 
  04 April 2010
there is definitively some problem with the color management in maya 2011 (why i'm not surprised?), strange differences from lens gamma 2.2, fg messed up
i'm stick with my old workflow with gamma nodes

p.s.
the one posted by david is the correct workflow... or at least it should be
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  04 April 2010
Thanks, David. Great found. I feel a lot more rest assured now as seeing your test. At least, my understanding to the settings from manual reading is correct. My settings (CM Render Setting, file texture color space, and defaultViewColorManager, monitor calibrated to sRGB) are exactly the same as yours except that I got a light and different material shaders used.

Plus, a confirmation from Dagon. I will stay with old-school gamma-correct-node based linear workflow for now for sure.......

later guys, be out shooting some HDRIs....
Jason

Last edited by jasonhuang1115 : 04 April 2010 at 04:33 PM.
 
  04 April 2010
Matt, David

Thank you soo much for clearing up some ill-informed opinions, and more importantly explaining we aren't going mad as there appears to be a 'hiccup' in the CM ( ).
You guy's should get some kind of commission and a big stick to ensure SP1(?) addresses these issues

Not that anyone will need this now but I uploaded a cruddy scene anyway
http://www.sendspace.com/file/xpsobz

Think just for now, I'll rely on the old way of doing things
 
  04 April 2010
Thanks to everyone for clearing this up, so I guess back to old workflow is way to go....
 
  04 April 2010
This is so sad...
Finally Maya has a built in color management, allows userfriendly linear workflow and then it's buggy...

I do have a question on this buggy 2011CM workflow.

Some of you set the Image Color Profile = Linear in the viewer Color Manager. Why? Mayas Help file clearly states "select the color profile of your image source file"

In my oppinion the source file (assuming jpegs) is a 8bit file and therefore sRGB and not Linear. Am I misunderstanding something here?
 
  04 April 2010
Originally Posted by mcscher: This is so sad...
Some of you set the Image Color Profile = Linear in the viewer Color Manager. Why? Mayas Help file clearly states "select the color profile of your image source file"

In my oppinion the source file (assuming jpegs) is a 8bit file and therefore sRGB and not Linear. Am I misunderstanding something here?

As it's an attribute of the ViewColorManager, I would interpret the "image source file" mentioned in the doc. as the rendered image, not your textures. In my test, I rendered the final output as EXR in linear, so I tell Maya Render View that the input image is linear and then apply a sRGB LUT for proper viewing on monitor. My 0.02. Hope that helps.
 
  04 April 2010
Originally Posted by mcscher: This is so sad...
Finally Maya has a built in color management, allows userfriendly linear workflow and then it's buggy...

I do have a question on this buggy 2011CM workflow.

Some of you set the Image Color Profile = Linear in the viewer Color Manager. Why? Mayas Help file clearly states "select the color profile of your image source file"

In my oppinion the source file (assuming jpegs) is a 8bit file and therefore sRGB and not Linear. Am I misunderstanding something here?


The image that you render is Linear. That's why you tell the Render View that the source is Linear.
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  04 April 2010
color management and LWF work fine in Maya 2011.

1. Enable color management in render settings (input-sRGB, output-Linear)

2. If any HDR image is used for IBL, change the color profile from "use default input profile" to "linear" in the AE of the HDR image's file node, 'coz HDRI is linear.

3. In the render view, choose 32bit display, and go to display > color management: image color profile - linear, display color profile - sRGB.

4. If using physical sun & sky, a mia_exposure_simple lens shader will automatically attach to the camera. Change the gamma of the mia_exposure_simple to 1 since you already gamma corrected the render view in step 3.

I'm not sure my workflow is error-free, but having tested several scenes, batch rendered out 32-bit exr files and imported into Nuke, they looked the same as the ones rendered out in the Maya Render View (by default Nuke sets all the HDRI's input color profiles to linear and displays with sRGB).
 
  04 April 2010
Originally Posted by Linalee: color management and LWF work fine in Maya 2011.

1. Enable color management in render settings (input-sRGB, output-Linear)

2. If any HDR image is used for IBL, change the color profile from "use default input profile" to "linear" in the AE of the HDR image's file node, 'coz HDRI is linear.

3. In the render view, choose 32bit display, and go to display > color management: image color profile - linear, display color profile - sRGB.

4. If using physical sun & sky, a mia_exposure_simple lens shader will automatically attach to the camera. Change the gamma of the mia_exposure_simple to 1 since you already gamma corrected the render view in step 3.

I'm not sure my workflow is error-free, but having tested several scenes, batch rendered out 32-bit exr files and imported into Nuke, they looked the same as the ones rendered out in the Maya Render View (by default Nuke sets all the HDRI's input color profiles to linear and displays with sRGB).


Hey, Lee,
We are using the same setting per se. Yeah, it will look the same in Nuke and Maya Render View, as I am getting that, too. But if you compare your Maya 2011 result with Maya 2010 (or before) result generated with the legacy linear workflow method in Nuke, you will see the difference as I posted in page #18.

I speculate the problem is from the internal value that Maya 2011 uses for gamma-correcting textures when the CM is enabled. The one used for Render Viewer is correct (as in Nuke). So, basically, you are sending a wrongly rendered image to two Viewers (Maya Render View and Nuke's viewer) that have the same sRGB LUT. Again, it is just my guess.


cheers,
Jason

Last edited by jasonhuang1115 : 04 April 2010 at 09:03 PM.
 
  04 April 2010
Originally Posted by Linalee: 4. If using physical sun & sky, a mia_exposure_simple lens shader will automatically attach to the camera. Change the gamma of the mia_exposure_simple to 1 since you already gamma corrected the render view in step 3.


The exposure shader does more than gamma. It compresses highlights and lowers the scene brightness by a factor of 5 which impacts all manner of other things. If you want your images to be strictly linear the easiest thing is just delete that node entirely. As I said earlier, you will need to lower your mia_sky brightness multiplier from 1 to 0.2 to compensate.
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  04 April 2010
Originally Posted by mattwood: you will need to lower your mia_sky brightness multiplier from 1 to 0.2 to compensate.

Why this?
Exposure simple is designed to work with sky&sun whit RGB unit conversion to 0.000100. Your 0.2, is personal and not good and Physical correct workflow.
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