Vray Tutorials |
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Gamma 2.2 setup (or my way of using the "linear workflow") [3] |
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Before you start
If you discovered this Vray tutorial page through a direct link or search engine, please note that you're on page 3 of the tutorial! Please complete page 1 and2 first if you haven't done so.
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The vray frame buffer
Untill now, we always used the max VFB. However Vray has it's own VFB, which is in fact a lot better. To use it, go to the Vray frame buffer and enable it. Next we have to disable max's frame buffer: in the common parameters tab, turn of the 'rendered frame window'.
Now when I render again, the image in the Vray frame buffer looks also very dark... This is because the max gamma preferences don't affect the vray VFB.
Luckily, the Vray VFB has it's own gamma correction. It's the small button labeled 'sRGB' on the bottom of the frame buffer.
When saving the image, you have to set the gamma to 2.2 again to burn it in, because the sRGB button is also only a display preview gamma correction.
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Color mapping
Color mapping provides a final way of burning in the gamma 2.2 curve. First we disable the srgb button again (the image will be very dark again).
Now in the Vray tab, open the 'color mapping' rollout. You can leave everything as is, you only have the change the gamma to 2.2.
Render the image again, and you'll see that it looks good now, without having to press the srgb button.
The big difference of this technique is that it applies the gamma 2.2 curve while rendering. The previous methods were all done after the rendering has finished (or as a preview only). This difference is pretty important, as it has serious consequences on image quality!
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Color mapping - quality
Here is an example of the difference in quality. Click the images to enlarge and view them side by side (or save them and view them one after the other in an image viewer). The first image is rendered with the color mapping technique, the second image is gamma corrected in post.
Take a close look at the building sides facing towards you (those who are not directly lit by the outside light). You will see that the lines running on these faces are noticably more jagged in the second image than in the first. This is because the vray sampler is sampling these lines on an image that is in fact pretty dark. With the color mapping technique, this image is already brighter during rendering so the sampler has less troubles identifying these lines.
Just remember that when you don't use the gamma 2.2 color mapping, you will need better sampling settings than when you do use it.
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Color Correct plugin
In fact there is still another way to gamma correct your textures: the color correct plugin. This is a free max plugin that can do color corrections on your textures, one of the corrections is gamma.
You can download the plugin here: http://www.cuneytozdas.com/software/3dsmax/
Altough you don't really need it, it's simply a great tool. Instead of having to go to the bitmap loader, you can simply set the image gamma in the color correct map. I sometimes use other gamma settings if I find that gamma 2.2 makes it too bright. Or use the color correct to desaturate an hdri map for example.
Another use is for the gradient ramp map from max. If you use this gradient with the gamma 2.2 setup, it will of course look different than you're used to. Put the gradient ramp inside a color correct map, and set the gamma to 2.2.
The same goes for normal colors. If you get an RGB value from the client, simply use color correct map: fill in the RGB values and specify a gamma of 2.2. |
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Gamma 2.2 setup: summary: my workflow
1. In max preferences enable gamma/lut correction and set gamma to 2.2.
2. Check affect color selectors and affect material editor.
3. Leave input and output gamma = 1.0.
4. In Vray color mapping, leave it set to linear, and set gamma to 2.2.
5. When loading a normal texture, specify it is gamma 2.2 in the bitmap loader.
6. HDRI maps don't need this correction as they are 1.0 textures.
7. Or use color correct plugin and specify gamma 2.2 there (don't do both!)
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Gamma 2.2 setup: notes
1. This workflow assumes you start from scratch with a scene. If you take an old scene and simply render it with gamma 2.2, it will look washed out of course. your materials, textures and lighting are not converted to work well with gamma 2.2.
2. I provide you with my workflow, if you like it, use it, if you don't like it, don't use it. Please don't email me trying to convince me it's no good, because it won't work :-)
3. ALL my recent 3D projects are rendered with this setup. |
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