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Gonzalo - Nuke VFX Fundamentals

31/10 Merging + Color

Concept of Premultiplication

Softwares like AE already premult layers

Page Up & Page Down to scrub AOVs

Instead of a layer system, the node tree system is a list of instructions

Merge Node and its operations:

  • over
  • mask
  • average
  • overlay
  • stencil
  • minimum
  • maximum
  • under
  • etc…

Reformat node: changing image size/format. Upscaling will result in the degradation of image quality. You can choose the interpolation methods but the result is often jittery. Can look at AI tools if upscaling is really needed.

Premult Workflow: Unpremult to divide by alpha -> do grading and CC -> then premult

When doing grading, we process and treat RGB separately from Alpha channels.

Colorspace and linearisation

32 Bit Color

Colour Matching Methods:
1. Edit the white point of the original colour, then adjust the gain.

2. Divide color, then multiply

Ctrl Shift-drag to get an average colour data

Alt + K for cloning nodes creates a reference copy of the node with linkages for all the parameters.

QC

Control highlights, mid-tones and low


Reflections

Today the main takeaway for me is the concept of per-multipilcation. To do image edits, we need to unpremult before doing any operation to the image. This is because there is extra image data in the channels that we are not aware. This information is new to me and I will definitely keep this in mind the next time when I do compositing.

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