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Color or tone mapping is an internal process that V-Ray uses in order to map the highs and lows of our rendered pixels; in other words, the drawing of the brightest and darkest values found in our renders. It does actually have a number of similarities to a camera's exposure control, or the response curve of the human eye to light levels found in its environment, as V-Ray's color mapping is designed to map the colors in our pixels to a range that is usable by, and viewable on, our computer display device. Of course, color mapping in some form is something that all render engines do.
Without this final translation of collected information into RGB pixel values, we would never get any images out of our rendering engine. One of the extremely cool things about V-Ray is that it allows us to make some pre-render choices as to just how this color mapping will take place, and so ultimately, how the colors in our final render will look. Before we go through a brief description and comparison of the color mapping types, however, we just want to quickly draw to your attention two parameters that almost all of the color mapping modes hold in common, and one that they all do.
Of course, we need to go to the Render Settings window, and pull that up. Then let's come along into the V-Ray tab. Let's just close up the Image sampler controls, and we want to open up our Color mapping roll out. Now, the parameter that all of our color mapping modes hold in common is this Gamma value. In fact, if we just very quickly flick through each of the color mapping types, and if you keep your eye on that Gamma value, you'll see that it is there for each and every one of them. Now, the gamma parameter can almost be thought of as a midtones control, but really it has been placed that to give us the ability to compensate for the gamma response curve of our display device.
To correct for a 2.2 gamma display curve, which is a typical Windows system setting, we would set, as we can see here, a value of 2.2. If we were using an operating system that used a different gamma response curve, say, 1.8, then that is the value we would place in this field. Now, the two controls that most of our color mapping types hold in common are these Dark and Bright multiplier parameters. In fact, the only color mapping type that we will find not using these controls is the Reinhard option, and you can see, those disappear.
These options are really working with the brightest and darkest pixels in our rendered image. They are controlling how the dark pixel of color values will be mapped, and the same with the bright pixels. Now, we've got a series of test renders here that we just want to demonstrate to you how changing these multiplier options can affect our rendered images. First, though, we just want to set our Gamma value to 1.0; that is how these render would taken. We just wanted to make certain that everything was really contrasting in here, because that really highlights the changes we make to, not only the Dark and Bright multiplier settings, but also our Color mapping types as well.
So, with that gamma change made, the defaults of 1 and 1 in the Dark and Bright multiplier would yield this particular result if we were to render our scene. Now, if you just keep you eye on the darker values in the scene, particularly around the edges of our image, if we just drop our Dark multiplier down, you'll see that that'll darken all of those values. You can really see how they drop down the brightness range. And of course, as you would expect, keeping your eye on those same dark values, if we double from the default of 1, to a value of 2, we would go to this particular render.
So you can see, if we take a look at the area under the stairs here, you can really see how those dark values are brightened up quite considerably. And as you would expect, exactly the same happens if we work with our Bright multiplier value. Let's just drop those down, first of all, to a value of 0.5, and this is the render we would get. And oftentimes, you will hear the Bright multiplier value expounded as a way of controlling burnout in our scenes. As you can see, it has gotten rid off our burnout, but because we've made quite a drastic change to the numerical value, we're getting some quite nasty artifacts showing up in here.
The Dark and Bright multiplier values really need to be tweaked very cautiously. We don't want to be making any drastic changes in them, because well, as you can see, we can cause more problems oftentimes than we solve. So let's just double our Bright multiplier default of 1 up to a value of 2, and that would give us this render, which as you can see, really does increase the bright values in our scene. So we've demonstrated how the Gamma, and Dark and Bright multipliers are working, but of course, we still need to look at the color mapping modes themselves.
So in our very next video, we're just going to walk you through each of the color mapping types, and we're going to show you the effect that it would have on our scene, as it stands at this moment in time.
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