The Math of Color Grading in Nuke

In this video we'll take a close look at the simple mathematical functions behind color grading operations in Nuke. We will only discuss operations that affect brightness, or value of an image. We'll save the more complex discussion of color and hue for a future video. 00:00 - Introduction 01:00 - Scene-linear and why it's important 02:30 - What is a linear function 04:30 - How the Grade node works 06:40 - Power functions and gamma 10:16 - Adjusting exposure in stops 12:10 - Compressing brightness with a logarithmic function 24:44 - How to take a complement with the invert node 25:44 - Keep your Toe under control 28:18 - Partitioning brightness ranges with ColorCorrect 30:56 - Make your own curves with the ColorLookup 30:31 - What the heck is RolloffContrast useful for anyway?! 34:48 - Histogram and why Nuke is not Photoshop For a more detailed look at using the Grade node, please watch Frank Reuter's excellent presentation on Color Correction - NUKE Basic Workflows: https://vimeo.com/76514569 The Desmos plots I show in this video are available here if you would like to play around with them: Linear Equation in Slope Intercept Form: https://www.desmos.com/calculator/ibou9opocw Slope Intercept Calculation: https://www.desmos.com/calculator/nvpksmtc5l Grade Node Math: https://www.desmos.com/calculator/gq1lq70fme Power Function (Gamma): https://www.desmos.com/calculator/pccpvr7kx9 Log Function: https://www.desmos.com/calculator/9j1qljhswu Log2Shaper Function: https://www.desmos.com/calculator/cigxtug2aj And here are some Wikipedia links for further reading: https://en.wikipedia.org/wiki/Linear_equation https://en.wikipedia.org/wiki/Proportionality_(mathematics) https://en.wikipedia.org/wiki/Complement_(set_theory) And a few other links I discuss in the video: Friends don't let friends view scene-linear imagery without an s-shaped view transform: https://cinematiccolor.org CinematicColor v2 - Common RGB Colorspaces : https://nick-shaw.github.io/cinematiccolor/common-rgb-color-spaces.html The image I am using to demonstrate scene-linear and an s-shaped view transform is available at cinematography.net here: https://www.cinematography.net/Valvula/valvula-2014.html And here's the nuke script if you want to play with it: https://codeshare.io/zyMb7D