Hello,
While ACES is a very hot topic in the computer graphics industry, color management and color space
have always been pretty daunting for the majority of artists.
So if you are part of this majority then stay tuned!
This video will show you a simple way to do it.
And we’ll show you how to work in an ACES workflow without getting into all the theory
behind it.
However, if you are interested in the nitty gritty details, we highly recommend for you to
check out Chris Brejon's website.
His website offers a great explanation on the theory behind color management, as well
as the reasons why every artist should use ACES.
And why is that?
Because in a nutshell, you gonna get far more realistic renders that also render even faster!
So you'll find the link to his website in the description below.
In Clarisse, color management is achieved through Open Color IO.
Open Color IO or, OCIO as it is commonly called, is an industry standard Open Source Library
that offers a complete color management solution.
It’s geared towards motion picture production with an emphasis on visual effects and computer
animation.
But before going any further, there are two fundamental concepts that we need to understand:
The Color Space is the space used by the rendering engine when performing internal color operations.
And the View Transform is then applied to the rendered image , which in turn transforms
the colors so that they are properly displayed.
In this video, we are going to see how to convert textures to an ACES color space and
how to apply a View Transform to your image view so that the rendered image is displayed
correctly.
So without further ado let's get started!
Ok!
So, first make sure to download the latest version of the OCIO ACES configuration.
You can find the link in the description below.
Once you've downloaded it and unzipped the content in your favorite folder, just launch
Clarisse.
Let's load the project found in the content of this tutorial and launch the render by selecting
the image.
Now, open Clarisse's Preferences Panel and in the Color Management section enable
Use Ocio Config File.
Finally select the OCIO file you've unzipped.
That's it!
Now we have access to ACES color spaces and View Transforms in Clarisse.
Now let's keep Scene Color Space to “use scene linear” and in the Default View Transform attribute
choose ACES.Rec.709.
Now every viewer of Clarisse like the Image View, Texture View, and even the 3D View will use the
Rec.709 view transform by default.
And the first thing we can see is that the highlights in our rendered image are no longer overexposed.
In our example we have some texture map files defining pure red, green, blue and yellow
colors.
Obviously these aren't the typical colors we usually find in nature but they will perfectly
illustrate the benefits of using an ACES color space and its wider gamut as compared to sRGB.
Okay, let’s connect the textures to the materials and use the green texture on the
ground material.
We'll be using the other textures for the spheres.
Now we have to convert these textures from a sRGB color space to ACEScg.
To do that, we first have to select our textures and uncheck Color Space Auto-Detect.
Then in the File Color Space attribute choose Utility - sRGB - Texture.
One thing to know is that most color textures like the ones we paint in Photoshop or the
ones we can find on the internet are encoded in sRGB 99% of the time.
A good workflow is to leave the textures as raw and then using a color space texture node
to perform the color space transformation from sRGB to ACEScg.
That way the material network is already prepared to render into another color space if needed.
This is very handy since when you reference in such material networks into a scene using
a different color space, you will just have to change the color space settings on the
Color Space Texture nodes.
This is perfect if you want to make reusable materials connected to a texture library.
Ok it’s time to render and write this image to disk.
In the 3D layer, make sure to set the LUT attribute to ACEScg before rendering.
And one Last thing, if you are using adaptive antialiasing make sure to always set the corresponding
Refinement Variance LUT.
In our case that's Rec.709 that can be found in the output sub-list.
Cool!
So now let’s use Nuke to compare our Linear sRGB and our ACES renders.
Again, like in Clarisse, you gonna have to load the OCIO config file.
So open the project settings and go to the color menu.
Set the color management to OCIO and select the ACES version in the OCIO config list.
Finally make sure to select the Rec 709 view transform in the viewer.
So here, I've loaded the ACES and Linear sRGB renders.
Since the sRGB render was saved in the Linear sRGB color space we have to convert it to ACEScg.
Just create a color space node and transform the image from Linear sRGB to ACEScg.
Now the colors on the 2 renders are matching.
However, we can clearly see a more natural global illumination color bleeding in the
ACES render which gives a much more realistic result.
Let’s take a look at some other renders.
Now in this render we can clearly see that the bounce from the ground on the pig looks way
more natural and realistic despite the fact that both scenes are sharing the same lighting
and materials.
Finally, let's discuss a very important point regarding adaptive anti aliasing.
Using ACES as a Refinement Variance LUT will speed up your render times.
Now that may sound strange but actually that's pretty normal.
Indeed, since the variance threshold computation is performed in a wider gamut, the renderer
converges faster using the Rec 709 transform than using the standard sRGB.
Now here, we can clearly see what I mean in the heatmap AOV.
In our sRGB render the sampling on the characters have almost reached the maximum number of
samples set in the renderer.
However in the ACES render we can see that way less rays were fired by the renderer which
leads to faster render times.
Now even better, if we look closely at the two images, not only is the ACES render quicker
but it also rendered with less noise!
So happy rendering with ACES and thanks for watching!