Without the 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, though, is that it allows us to make some pre-render choices as to just how this color mapping will take place, and so ultimately we can affect a little bit how our final renders will be looking.
So of course we need to go and open up the Render Setup dialog for ourselves, we want to come into the V-Ray tab, and I am just going to close up everything except our color mapping rollout. Now, the parameter shared in common by our color mapping modes is this Gamma value. In fact, if we just very quickly flick through each of the options available, you can see that, that Gamma parameter stays consistent. It is available for each and every one of them. Now the Gamma value can be almost be thought of as a mid-tones control, it is really placed there to give us the ability to compensate for the Gamma response curve of our display device, and because it is available in each of the color mapping modes, we can do this irrespective of the color mapping we want to work with.
To correct for a 2.2 Gamma display curve, which is a typical Window system setting, we would use a value of 2.2 in this option, just as we have here, and the render that we can see is the end result that we would get. If of course we were working with an operating system that has a different Gamma response curve, or we just wanted to make a change for artistic preference, then a value of 1.8, for instance, is something that we could work with, and this is the image that we would get. You can see just a little bit of a shift down in terms of the mid-tones, the image is a little bit darker with the Gamma 1.8 option.
So that's the parameter that all of our color mapping modes hold in common. We want to look now at the Dark and Bright multiplier, which are parameters-- these are controls that most of our color mapping modes are going to be working with. So if we just minimize our render frame window and just pull up the RAM Player for ourselves, again, just remember all of the images we are looking at here are available in the Exercise_Files folder in your Render Output and Ch02 folder. So I just want to set the Gamma value here to a value of 1.0, because each of these renders were taken using this value.
Whenever we are rendering with such a high levels of contrast in our scenes, we really see the effects of the Dark and Bright multipliers and the color mapping modes as well, so that is why we just use this value for these particular renders. Now, the Dark and Bright multipliers-- as their name would suggest--control the darkest and brightest values found in our rendered image. If we were to take a render with the settings as we see them now, you can see this is the way our image, our render would turn out. If we to make changes to the Dark multiplier, for instance, if we were to drop the Dark multiplier down--I just want you to pay attention to the dark values just around the edges of our render-- and if we take this and drop it down to a value of .5, and then take a look at the result in render, you can see just how all of these dark areas all drop down in value.
So you can really see what the Dark multiplier is doing there. Of course, if you keep an eye on those same values, as we go up to a value of 2, so now everything around these edges is pushed quite a bit. And if we just compare it to our start point, you can see all of these dark areas really do brighten up. And of course the same is true of the Bright multiplier itself. So let's set it back to 1, and if we go to a value of .5, this time we want to pay attention to all the brightest spots in our image. So for instance, where we get the light blowout here, again, let's go back to our reference. You can see we've got very bright areas where the light is blowing out our material, and if we go to the Bright multiplier render of .5, you can see all if that blowout is gone.
Now, just a word of caution here, oftentimes you do see the Bright multiplier recommended as a method of handling blowout or burnt areas in the scene, but as you can see, because we have made quite a drastic change to the Bright multiplier, we have quite bit of artifacting going on inside of our render here. So generally for subtle tweaks the Dark and Bright multipliers work well. If we want to get rid of something very severe, then making changes of this order, of this magnitude, really not a recommended way of doing things. And again, if we keep an eye on those bright areas, if we really push up to a value of 2, you can see our resulting render really does have quite bright values in it indeed.
