Maya 2017 Arnold Color Manager

# 1 01-02-2017 , 10:50 PM

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Join Date: Jan 2004

Location: Bolton - UK

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Hi guys hope someone can help me out here.

Been playing around with Arnold and loving it. But I have hit a wall here and can`t find anything about this that makes sense.

Just install a clean Maya 2017 service pack 2 which comes with Arnold MtoA 1.4.0.0 Arnold core 4.2.15.1.

Now I am trying to setup a Linear workflow - something thats easy to do now in Maya 2017 they say.

Just go into prefs and color management and make sure its turned on.

user added image

(if you right click and view image you can see the text clearly.)

Now I have a AR Standard martial applied to my object and went of to render. Rendered fine but when I saved the image it comes up much darker than the render window when viewed else where.

user added image

Now the out of Maya image looks better but I want to get this right - which one is correct, and what am I doing wrong. Planning on doing some textures as well so need to make sure I get that right aswell.

Why did they have to change it all - I used to get this .....

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# 2 02-02-2017 , 01:48 AM

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Join Date: Dec 2006

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It's likely that you're saving an uncorrected image while the render view is using a gamma of 2.2. The uncorrected image will be darker and more saturated. Which one is "correct" depends on what comes next. If you're looking to do color grading and effects then a RAW or uncorrected image is more flexible and you can apply gamma correction in post. However, 8bit formats like jpegs cannot store actual RAW information as it just doesn't have the bit depth capacity. Personally, exr is my go to output format and even though I paint textures in 16bit, most of the time they end up as 8bit (unless it's a displacement or normal map) and they look just fine.

- Genny
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# 3 02-02-2017 , 01:26 PM

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Cheers Gen - Really helped alot - But this process still is very confusing.

Saving the images out as EXR has let me play with the files in Photoshop

I did also find that there is a view transform option in the Arnold view port and setting that to "Raw" instead of Gamma2.2 gives me the same look as the saved files and there is also an option to save the images as Color corrected. None of this is remotely explained anywhere in the number of tutorials I have seen.

I just hoping this does not blow up in my face once I get some textures on it.

But really grateful I have a workaround for it now - Cheers.

Here are some renders of just the shadders

Ver 01

user added image

Ver 02

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# 4 03-02-2017 , 02:12 AM

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It all hangs on the fact that a linear workflow produces the most believable lighting and there's no achieving this unless gamma is addressed. In a nutshell, gamma correction boosts the overall values of pixels to compensate for the fact that the voltage that monitors use to power said pixels just doesn't allow for the colors to look quite how we'd expect. This is why RAW images look dark and saturated and it's why common images like jpegs for example, have the compensation embedded in order to look normal. And it's why lighting without a linear workflow would involve a boat load of lights with all kinds of intensities, decay rates and shader tricks to balance out the illumination.

The color management's input color space allows you to counteract the embedded gamma correction (sRGB suits the typical 8 bit image and of course Maya's color picker now has color space options). The now proper colors are passed into the rendering space for processing (you can change this if the output is for projectors or to be comped with film footage etc) then there is the view transform which is the color space used for simply previewing output in a way that looks right to eyes of us mere mortals (both Maya and Arnold's render views allow you to save the image with the view transform baked in).

I think it causes confusion because of how messy linear workflow was in older versions and then the 2015 color management was half baked as it only corrected textures and not swatches so a bunch of gamma nodes were still necessary. And the only reason I don't use 8bit images for displacement and other data maps is because of banding and artifacts otherwise 8bit is fine (or else I'd have to ditch my Arroway CDs lol).

- Genny
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Maya 2017 Arnold Color Manager

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