>> 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.