Linear Workflow and Gamma Correction Part 3

In this, the third of what will now be four parts, I look at the manual method of setting up and working in a linear workspace with 3ds Max and VRay.

I'll try not to repeat any of the points made in earlier articles, but it is important to reiterate that all inputs and outputs require some form of gamma correction.

The Input

The method I am recommending is to add a colour correction node to your bitmaps and colours, and then apply an inverse gamma curve to that by setting the RGB gamma to 0.4545. You should remember this value from the first article - if you don't, I'd advise you to take another look.

This will not doubt be a change to your existing workflow and to start with, you will probably forget to apply this additional node when creating materials but it really is the simplest method and most flexible.

It gives you absolute control over the amount of correction you are applying and allows you to make some materials darker or lighter depending on your preference, as well as tweaking the other options that the colour correction node offers.

The Output

As mentioned in part 2, there are slightly different workflows depending on what you are planning on doing with the render after the 3d application. If you aren't going to do any post processing then you will need to bake the gamma correction in to the final render. VRay does this with the Colour Mapping rollout in the Render settings.

Baking this gamma correction is also the method I choose when rendering out test scenes as it gives instant feedback without the need to get it into post. If you adopt this method, you will need to remember to revert back to the default of 1 when rendering out the final image.

There is of course a tool for this that can also help with previews. What you will need to do is, enable the VRay frame buffer from the render settings, return the gamma correction colour mapping to 1 and then toggle the sRGB button to apply the gamma correction.

The correction is made after the image has been rendered, so there will be times when you turn it on to correct and brighten up the image, but because there wasn't enough sampling in the darker areas, it will become noisy. This is the trade-off for sheer ease of use! Personally, I don't use this method (for the above reason) but it is a very useful tool.

By now you should be familiar with both the concept and workflow involved in manually setting up a linear workspace with 3ds Max and VRay. It may be worth your while getting to grips with this now by testing it out on some of your old scenes and seeing for yourself a marked improvement.

Part four of the series is on its way. In the meantime, if you'd like to find out more, give the team a call on 03332 409 309 or email 3D@Jigsaw24.com.