How to do it...

Before we start this recipe, let's take a look at how the scene has been set up for you. We are providing the level we mentioned in the previous section as a starting point for you to follow along and you can find it in the following directory: Content / UE4ShadersAndEffects / Maps / Chapter02 /.

The name of the scene is 02_02_ColorGrading, and it includes several elements that are going to be useful for us. At this point, you are probably already familiar with this scene after all, we've used it in the previous recipes to start learning about the post process volume. As we are going to delve a little bit deeper into that same actor, we've also included it in this new level. Additionally, we've decided to add a cinematic camera just so we have a fixed point that we can use to compare the different visual changes we are about to introduce.

Of course, and as should be becoming a bit of a tradition by now, feel free to follow along with any scene you might have created yourself. The key components to include are the post process volume, as always, and perhaps a cinematic camera for a bit of flair. Having an interesting environment in which to test the following steps we are about to perform is always nice, but not essential as we are going to be color grading the whole scene, the visual changes are going to be quite evident. In any case, rest assured, you'll have access to the scene you see if you need it.

Wile we're talking about that camera actor we've included in this level, let's allow ourselves access to its viewpoint. To do so, head over to the upper-left corner on the main viewport – hopefully, you can locate a little button there that, once clicked, shows a dropdown menu that you can use to access the existing camera. The view you will enter is something such as this:

Having access to that camera perspective will enable us to better visualize the changes we are about to make. And all of those changes, as stated, are going to revolve around the Color Grading tools inside of the Post Process Volume actor. You can find the different settings if you select the appropriate actor and look for the Color Grading section within the Details panel. You should be looking at something like this:

With that out of the way, let's properly start setting up a different mood for this scene by playing with the properties we can find under the Color Grading section. As you can see, the scene we are dealing with is quite warm it feels cozy, inviting, and you could think that it was someone's house. This is mainly happening because of the overall color of the scene, where the wooden floor and the soft walls (along with the little festive prop) add to that sensation. We are going to change that feeling with the power of color grading:

1. Head over to the Details panel after making sure that the post process volume is selected. The first option we are going to be changing is the White Balance; expand that section and tick the Temp checkbox, and change the value to something lower. I'm going with the value 4,500, which makes the scene already feel colder.

1. Leave the Tint checkbox unticked if you want, as that allows for the modification of the cyan and magenta color ranges. If we decided to use it, we would find ourselves modifying the White Balance temperature tint between those two colors, something we don't want to be doing for this exercise:

As you can probably already tell by looking at the previous screenshot, the scene feels much colder already. Be sure to check the How it works... section to fully understand how modifying the White Balance setting affects our scene. Let's now continue to change the feel of the scene by tweaking a couple more settings.

While still in the Details panel, let's take a look now at the following categories within the Color Grading tab: the Global, Shadows, Midtones and Highlights. All of them control the same properties of the image, but they affect different color ranges. We will be able to change settings such as the saturation of the image or the contrast for each different color spectrum. For instance, modifying the Saturation within the Highlights will affect only the brightest values within our image. Doing the same on the Shadows section will do the same but on the darker tones.

With that in mind, let's continue to modify our scene:

1. The first operation we will be performing is the adjustment of the shadow intensity. Find the Gain property under the Shadows category and modify its value to something like 2. This will effectively wash out the shadows.
   Now let's change the gain of the shadows:

1. We also want to desaturate the image a little bit, just so we move away from the original warmth we were seeing initially. Head over to the Saturation section of Midtones, where we can apply a lower value than the default 1. I've chosen 0.75 just to make things a bit more pale:

With all of those changes in place, we can now compare the initial scene we were looking at against the current state it is in. If you want to do so, just select the Post Process Volume you have on your scene and uncheck the Enabled option under the Post Process Volume Settings section inside the Details panel. Ticking that box on and off will let you toggle the Post Process Volume that is affecting our scene. Let's take a look at the results:

They feel quite different, don't they. The changes might be subtle, but they are definitely there—we are now looking at a much whiter scene, which feels colder overall and is less saturated. While the first image can make you feel warm and cozy, the second one is a bit more neutral. However, let's not stop with the adjustments just yet! Now that we know the basics, let's get a bit crazy. What if we gave the scene a bit of a horror touch? 

1. To do so, let's start by cranking up the Contrast of the Midtones to something like 1.5. That should make the scene pop out a little more:

1. Something we can also tweak is the value of the Saturation under the Highlights section. Let's set that to something really high—I've chosen 1,000 for this particular scene. Doing so should really make the brightest parts of the image stand out in an unnatural way, which could make the viewer feel a bit uneasy and on edge:

1. Finally, let's apply a color tint to the scene. Horror movies and psychological thrillers often make use of a greenish tint when they want to highlight the fact that something is wrong or just to create a bit of an atmosphere. If you head over to the Misc section of the Color Grading tab, you will find a setting called Scene Color Tint. Changing that to a greenish pastel color should give us the result we are after:

Look at that! With that final touch we've covered most of the settings that we can tweak inside of the Color Grading post process category. Now that you have an idea of what they do and what they affect, you may want to play around a little bit more with them to get more familiar and confident. The job of a color grader requires patience, as tweaks and corrections need to constantly be applied until you get to the look you are after. In spite of that, the tools that we have at our disposal are quite powerful and should serve us well. Have fun with them!