Fig.05b – Output Gamma: 1.0. This is the render exactly as it is saved out, without any gamma correction. Although it looks strange, this is the result we want. It will be gamma corrected to 2.2 for final output.
By completing the steps above, we have told 3ds Max to display everything with a gamma of 2.2, but saved the rendered output to disk as Linear.
A quick note about Output Gamma: The steps I have outlined assume you are rendering out to a high bit format (explained later in this tutorial). For the best flexibility, you want the most tonal range you can which is why you save out with a gamma of 1.0. If you don't need to do any compositing or color correction, you could set Output Gamma to 2.2. As shown above, the render will look as expected. This could change per project depending on the required output, but I find it easiest to set to 1.0 for everything, and keep my workflow consistent.
Because we have told 3ds Max that all textures have a gamma of 2.2, when importing Normal Bump, Displacement or Vector Displacement maps you must specify a gamma of 1.0. The reason for this is that these images are based purely on data. This could vary though, depending on how you are generating the maps and what formats they are saved into, so I do recommend trying both manually setting gamma to 1.0 on import and letting 3ds Max assume a gamma of 2.2. Though you will only need to test this if you are getting unexpected results. In most cases, setting gamma to 1.0 for these types of images is the standard. You can do this directly from the Open window when importing a texture. Just check Override Gamma and make sure it is set to 1.0 (Fig.06).
Now 3ds Max knows exactly what to do with our images and renders. But what about our chosen render engine? Does it know how to interpret everything and how we want to save it? Let's check it out!
Part 2: Setting up your Render Engine
Scanline and mental ray
By default, there is nothing you will have to change for these render engine, unless you are using exposure controls.
To utilize a linear workflow in V-Ray, you will need to change some settings in the V-Ray Color Mapping rollout in the Render Settings (Fig.07):
• Type: Linear multiply
as it is truly linear. You can read up on the alternatives here: http://renderstuff.com/best-vray-settings-antialiasing-and-color-mapping-cg-tutorial/#VRay_Color_mapping_rollout
• Clamp Output: Disabled
when saving to a 32-bit file, as clamping the render means you will lose information. This can cause artifacts though in certain situations, so keep an eye out for this.
• Gamma: 2.2
. This tells V-Ray to calculate everything for an eventual output to a gamma of 2.2. If it was left at 1.0, you could end up with artifacts from things like GI and antialiasing.
• Don't affect colors (adaptation only): Enabled
. Tells V-Ray that the Gamma: 2.2 we just set is only to be used for calculations, and to not apply it to the final render.
• Linear workflow: Disabled
. Do not
tick the Linear workflow box. Although it sounds like exactly what we want, it is actually an old, brute-force method of converting a scene, and isn't appropriate here.
A note about the V-Ray Frame Buffer: The V-Ray Frame Buffer doesn't take into account the Gamma and LUT display settings in the 3ds Max preferences. To enable correct previewing, you have to turn on the sRGB button on the bottom toolbar of the V-Ray Frame Buffer.
The only change you need to make to the finalRender settings is the AA Gamma located in the Anti-Aliasing rollout in the Render Settings. To access the Anti-Aliasing Settings, click the hammer icon in the rollout. Change AA Gamma to 2.2 and you're all set (Fig.08).
So, 3ds Max knows how to process our images correctly and our render engine knows how to process the renders. So how do we save out our wonderfully linear images?