Blender-School Render Raw 1

I need to get back into more structured learning. I have too many urgent things to learn than I can count using my fingers. 

• I should do a minimum of three 1-hour training blocks per week.
• These blocks must include note-taking and exercises.

I think the following are a priority:

• Render Raw
• Photographer 5x
• Lens-Sim
• Hard-Ops
• Substance Painter
• Geonodes
• Geoscatter
• PBR Material and Material Generator (revision)
• Extreme PBR

More general learning:

• Environmental and terrain tutorials
• True-Assets revision

This list was pulled from the air. I may suddenly realise there's something important missing.

So to start, let's take a look at Render Raw.

Render Raw (Featuring Creative Shrimp's mini-course on colour correction)

See Render Raw's full documentation.

Basics

In Blender, outputs are generated in RAW but are then baked into a colour space for display. This baking happens through a View Transform model, such as AGX or the older Filmic. These view transforms take the Colour Gamut (colour model that handles chromacity (measures hue and colourfulness) and filter them through a transform process that we often refer to as "baking", which indicates a one-way process that can't be reversed because it loses data. If you don't use a View Transform, then your high-bit-depth output simply gets clipped as it transitions into the Closed Colour Space. It often results in blown-out images that just look bad.

Colour Gamuts set the range of colours that can be displayed. Blender uses sRGB (standard RGB) because it offers a good, easy-to-use and accurate colour presentation across various devices and formats. Note: Internally (pre-output), Blender uses the Linear Rec.709 because it's physically accurate and linear, so good for the technical aspects.

Colour Gamut (1931 CIE)

Default gamut sRGB through the AgX View Transform.

RAW is the uncompressed high bit-depth image format, such as EXR, that contains "raw" colour data. This format yields extremely large files. It's normal to use a View Transform to bake the colour data to match the expected view formats.

ACES is the Academy Color Encoding System and was designed for the film industry to provide a standard so that different creators could have consistency as they worked on each other's outputs. ACES isn't better than AgX; it has limitations like Filmic, but it is the industry standard, and sometimes consistency is better than capability when you know how to work around limitations.

In Blender 4.0 the View Transform moved from Filmic to AgX. This caused a bit of a stir because AgX tended to make outputs "pop" a bit less. However, AgX is just objectively a better and more sophisticated View Transform model. Filmic doesn't support wider gamut colour spaces, such as P3. It also has a lower dynamic range. Although, with middle-range colours and intensities, the two View Transforms provide comparable results. For more information, Christopher's 3D's excellent introduction to AgX.

In a nutshell, rendering to RAW instead of through a view transform preserves light and colour data that you can modify to enhance the look of the output. Previously, this tweaking would be done outside of Blender in a separate image processing app, such as Photoshop/Photo/Lightroom or a compositor, such as Premiere or DaVinci Resolve. For this, you'd  save your outputs in a high bit-depth format like EXR that preserves colour data.

Render Raw

It is a Blender addon that provides tweaking tools, similar to those found in external apps, within Blender and available in the viewport to preview. However, they are still applied at the end of the rendering pipeline.

Pre-grade: A change made before the render pipeline (and View Transform) as part of a scene's setup
Post-grade: A change applied to a render output, usually in the compositor

Render Raw works with both Pre and Post-grade changes as they are applied through the compositor (but under the bonnet, as you don't need to touch the compositor yourself).

Nodes and their grade position

Post-formation changes are more lossy because they are applied to pixels that have been baked out of a View Transform. They also are not protected from breaking out of the available colour/intensity. Post-formation colour tweaking allows you to achieve the colours you want; however, you need to be careful as you make your changes.

Once Render Raw is installed, you enable it through the N-panel. Its tools then appear within the panel, or under the Render tab's Colour Management panel.

N-Panel view

Transform: The View Transform, as listed above.

Presets: A set of parameter adjustments that get general effects, such as a contrast punch

Exposure: Light levels. Lower for moody, higher can look washed out. It's safer to be slightly above as you don't lose too much definition.

Gamma: Not intended for mortals. It's not an exposure setting, it's not a colour grading instrument, it's a technical setting. Leave it at 1.

Colour correction example

You'll see in this example how post-formation tweaks could filter out the flame's form and avoid AgX's "salmon" colour profile. This is why Render Raw uses both pre- and post-formation adjustments.

Starting point

See the colour in the visor highlights has clipped with artefacts on the fringes.

Colour boost is less likely to blow out colours.

Moody with saturation

Lesson takeaway: 

• No amount of colour correction tools training will tell you what looks good. I need to delve into colour theory, photography and cinematography. 
  
  
• Keep RAW for access to the source colour data and the most options for making image adjustments.
  
  
• Make Pre-formation changes to have the source colour data to work with, but Post-formation changes are sometimes just what you need.

Part two of this lesson is coming soon, although I grasp what the tool does much better now.