>> Welcome to Unreal Tips
and Tricks. In this week's episode,
we will be looking at how best to use
the Color Grading tools. We will start with a brief look at some important points
to consider. Then we will jump
right into the workflow. Before you get started,
it is a good idea to ensure you are working in the best
environment for Color Grading. Your workstation should be
in a lighting situation that is not too bright, and it is best
to work on a monitor that has full support
for the SRGB color gamut. Standard RGB is the most
commonly used color space on digital displays, originally designed
for use with CRTs. And it is the color space you
will be working with in Unreal. You can also use a monitor that is calibrated
for the Rec 709 color space, as Rec 709 and SRGB
are virtually identical. When purchasing a monitor, it should have
a percentage indication of the SRGB color
gamut that it supports. Values over 95 percent, and even up to 100 percent,
are not uncommon. A monitor with a high contrast
ratio of 2000 to 1 or better, as well as a good
peak luminance, and low black levels
is also recommended. Most workstation monitors
come pre-calibrated, but depending
on your lighting conditions, and over time,
you may need to recalibrate. For that, I recommend something
like the X-Rite i1Display Pro. Unreal can output to both
low dynamic and HDR displays. For more information
on the topic, check out
the Unreal documentation under Engine Features,
Rendering and Graphics, High Dynamic Range
Display Output. This workflow will work on both
LDR and HDR displays. While Unreal still has support
for lookup tables, the recommended workflow is
to use the Color Correction settings instead,
as these settings will better ensure the Color Balance
looks the same on all displays. Finally, avoid using
Color Grading as a way to fix Texture,
Lighting, or Exposure issues. Those issues should be solved
first by adjusting the Textures, Materials, Lights, and Exposure
settings, respectively. Before we get started
with Color Correction, it is a good idea to disable
Eye Adaptation, or Auto Exposure settings. There are a couple of ways
to do this. First of all, we can go
into our Project Settings, and from here go to Engine,
and then Rendering. Then scroll down
to the default settings. From here,
we can disable Auto Exposure. Another option,
if you have already got a Post-Process Volume
in your scene, we can select that Post-Process Volume,
and then open Exposure under Lens, and select
Min and Max Brightness, and set both of
these values to 1.0. When judging the Color
Balance of your scene, it is a good practice
to drop in some reference Objects designed to assist us. The reference Objects that are
most often used in photography are a gray ball and chrome ball,
as well as a color chart. Fortunately, Unreal comes with
these helpers already built in. To get access to them, we need to go
to our Content Browser, and then open View
Options, and in View Options, we want to make sure
that Show Engine Content is checked. From here we need to open up
the Sources Panel, and then we can search
under Engine Content, Editor Meshes,
and then Color Calibrator. The Object we are looking for
is SM_Color Calibrator. Go ahead and drag
that into the scene. We will focus in on that Object, and we will position it
in our scene so that we can make use of it.
It is best to rotate the Object, so that the color chart
is perpendicular to your main light source.
The easiest way to do this is to select
the main light source -- in this case it is going to be
our Directional or Sunlight -- then I am going to
copy the Rotation by right-clicking on Rotation,
choosing Copy, then I will reselect
the Color Calibrator, right-click on Rotation,
and choose Paste. Now we only need
the Z Rotation, so I am going to change
X and Y back to 0. Now, in some cases, you will not want to zero out
the X and Y Rotation, so you will want to keep them
exactly as they are. It really depends upon
where your source light is in the scene. The idea is that you want to
make sure the light is hitting the front face of the color
chart exactly perpendicular, so that there is no shading
effect across the surface; you want it to be full bright. In this case,
I think we are okay. All right, let us look at
the Color Grading workflow now. There are two sets of tools
we will be using, and both are found
on the Post-Process Volume. When Color Grading,
the first step is to adjust the Project's Tone Mapper,
or Contrast. Unreal's film tone mapper
uses the ACE's, or Academy Color
Encoding system. This system is an industry
standard for film and TV. It is the closest approximation
of the entire color gamut available
to the human eye, and what it essentially does is, it maps the HDR content
from Unreal onto low dynamic range displays. When adjusting
the Filmic Tone Mapper, you want to adjust it
for a project-wide look. The settings we have available
to us are Slope, Toe, Shoulder,
Black Clip, and White Clip. These settings are used
to control an S-Curve. Slope controls the overall shape
of the S-Curve. Keep in mind
that lower values here will make
the contrast very dull. Toe controls the bottom
of the S-Curve, or where the darks
and blacks are. The best way to adjust the toe is to find a dark spot
in your scene, and then adjust it there. Adjusting the toe can help to
lighten areas that are too dark. Shoulder is used to control
the top of the S-Curve, and the best way
to adjust the Shoulder is to find a bright spot
in your scene, and tweak it from there. It is generally best to leave
Black Clip at a value of 0.0, and then White Clip
will allow you to choose where the whites
begin to clip out. You can easily disabled
the Filmic Tone Mapper by simply bringing up
the console with the tilde key, and then typing
R.tonemapperfilm, and then 0.0 to disable it. If you need to re-enable it,
simply type it back in again, and type 1.0 instead of 0.0. Keep in mind that this
does not completely disable all Tone Mapping. What it does is, it disables
the Filmic Tone Mapper, and then falls back
to the default Unreal Tone Mapping system. Remember, it is a best practice to settle on a film curve
on a Project-wide basis. Changes to the film curve can have dramatic effects
on Color Grading. Working this way
helps ensure consistency, much like the film world, where a single film stock
is used for the entire Project. After we have adjusted
the Project's Tone Mapper, we are ready to begin tweaking
the actual Color Balance, using the Post-Process
Volume's Color Grading settings. These settings can be used
on a shot-by-shot basis, from camera to camera,
or scene to scene. The first thing
we will want to do is to adjust the White Balance. Under White Balance,
we will find Temp. This is the Temperature. It is defaulted to a value
of 6500 kelvin. Generally the way you work
with White Balance, much like photography,
is to find a spot that is actually white,
such as here on our color chart. While looking
at that white spot, you can then adjust
the Temperature until it looks right. Obviously lower values
will make the scene look cooler, while higher values
will make it look warmer. The look you are going
for will determine the final Temperature
that you choose, but a typical sunny day
is at a Temperature of about 5500 degrees kelvin. After we have set
our White Balance, we have Global, Shadows,
Midtones and Highlights. It is best to start with Global
and do as much as you can, and once you have finished
changing the Global settings, if you need to continue
to color correct, then move down to Shadows,
Midtones and Highlights. Under Global, you are going
to find the primary controls. These are going to be
Saturation, Contrast, Gamma, Gain,
and Offset. Saturation is obviously
for color purity, Contrast, again,
is for Tonal Mapping. Gamma controls Midtones,
Gain controls Highlights, and Offset controls Shadows. Starting with Saturation, this allows us
to control color purity. You will see that we have
a color wheel, as well as a slider
underneath that color wheel that controls Intensity, and to the right of that we have
R, G, B, and Y sliders. We can also switch to
High Saturation Value mode. We can use
the Intensity slider here to very quickly change
our scene to black and white. Opening up Contrast, we can see
we have a color wheel again, but unlike the Saturation
color wheel, this wheel has a complementary
effect to the scene. So if I were to pool the color
over to a warm orange-ish color, we can see what is happening is that the Highlights
of the scene are orange, while the shadow and dark areas
are light blue. Again, we can control
the contrast intensity with the slider. Remember that Gamma
controls the midtones. You will find that
if you would like to tint the entire view
to a certain shade, this is the best place to do it. Gain allows us
to control the highlights. Keep in mind that all of these
settings have some overlap; for instance, Gain will not
only affect the highlights, but you will see as I drag
this Gain towards Blue, it is also affecting
the Shadows. We can help to alleviate
some of that overlap when adjusting the Gain. To do that,
we will go back up to Gamma, and we will make sure
to drag the color wheel to the opposite side
of the wheel, or the complementary color.
As you can see, I am on the opposite side
of the wheel from Gain, and now my shadows have less
of a blue cast to them. And finally, with Offset,
we can control our shadows. Now if after you have adjusted
all of the Global settings you are still not
quite happy with the look, and you need to adjust
something specific, say, the shadows, you can scroll
down a little further, and you will have your Shadows, Midtones, and Highlights
rollouts. So for instance, if I wanted
to tweak my midtones further, I would open Midtones,
and then perhaps open Gamma, and then maybe we will give this
a slightly blue cast, and adjust the Intensity. Of course, Color Correction
and Color Grading are a subjective art,
and Unreal's Color Grading tools are going to allow you
to do both color correction and special effects
quite easily, once you understand
how they work. If you would like more
information on Color Grading, check out
the Unreal documentation at the link on-screen. Thanks for watching, and we will see you on the next
Unreal Tips and Tricks.
