Introduction to Digital Colour Theory
Taught by Charles Poynton
- Course Number:
- Software Version:
- Original Run Date:
- March 2017
- 5 hours 6 minutes
Taught by leading industry expert Charles Poynton, who literally wrote the book on the subject (several books actually), it assumes a working knowledge of the industry but not that you are a maths wizard. Charles has designed the course to be aimed at someone “whose main interest is not the maths,” with loads of helpful diagrams, graphs and examples to help participants quickly understand these key technical concepts.
This course is ideal for vfx compositors, TDs, editors, technical DOPs wanting to follow their work into post, or simply anyone in the production chain who wants to gain a solidunderstanding of colour science as applied to the pipeline.
Charles Poynton is a freelance color science expert specializing in the physics, mathematics, and the engineering of digital colour imaging systems, including digital still cameras, digital video, HD, VFX/CGI, digital cinema and digital intermediate (DI) systems. He was involved in engineering wide colour gamut systems, an expert in colorspaces such as DCI P3 RGB and Adobe RGB and about 20 years ago he was the guy who decided that HD should have square pixels (!) Charles has taught several more senior courses inside fxphd, but this course is designed for those who do not want the maths but do need to understand how a colour pipeline works.
The fast forward program is standalone instruction with immediate download but does not include access to our discussion forums or VPN software. Samples used during the course are available to download, and that includes a pdf handout with notes and materials. Once you purchase the course, you can immediately download all class instruction videos.
(WARNING: The presenter is Canadian; colour will be spelled with a “u”!)
Class 1: Image matrixGetting the best images has to start with the camera and how the camera sensor deals with the images presented by your choice of lens. While we think the sensor records a full RGB image it really does not – it records some light levels and then this is interpreted by the camera’s electronics. Charles explains what an image matrix is and how to acquire colour information at the camera sensor. He also demonstrates additive colour mixing.
Class 2: Lightness, colour and video terminologiesBeing able to work successfully and produce accurate and predictable color science requires first and foremost knowing what all the key terms mean. In this class Charles demonstrates subtractive colour mixing and the ‘gamut’ of CMY colour space. Charles clarifies a bunch of common lightness, colour and video terminologies so you have the tools to build your own correct colour pipeline.
Class 3: 18 percent grey, the ‘code 100’ problemHave you ever wondered why an 18% grey patch looks actually mid grey, or exactly how very simple operations such as contrast work? In this class you will learn the theory behind 18 percent grey, the ‘code 100’ problem. You will also learn the use of different gamma settings and the confusion over brightness and contrast settings.
Class 4: Display and its viewing environmentColour science is not something that happens in the vacuum of a theoretical computer. In reality your working and display environment is key. In this class we look at the relationship between your display and its viewing environment, plus some common terms of image control and what they really mean. Charles also explores the technical parameters of RGB colour space and how the pixel values map to luminance at the display. We also look at how modern HD cameras maps tristimulus (or colorimeter) values into video signal levels and some of the common adjustments you can make in the camera.
Class 5: RGB colour transformed into YCbCr colourThe easiest colour space to understand is normally just a variant of RGB colour, but we will need to be able to understand moving between colour spaces and what the pitfalls are. This class you will learn how RGB colour space is transformed into YCbCr colour space, and the different flavours of colour “sub-sampling” are explained.
Class 6: Colour gradingNothing is more important to the emotion of a scene than its colour grading. Over the last decade colour grading has become more prevalent and more vital to understand, so much so that this class is completely devoted to Charles explaining the theory behind colour grading.
Class 7: BT709 standardSince almost the invention of displays one tool has been used: Colour Bars. In this class we take a real look at colour bars, – what are they – what can you learn from them and more specifically the ‘pluge’ (short for “Picture Line-Up Generation Equipment”). The pluge is part of a modern set of colour bars and it aids in adjusting the bottom of the luminance range to avoid either washing out the black tones into grays or collapsing picture information into clip. Charles gets into details of the BT709 standard and how absolute illuminance affects the image appearance at the display.
Class 8: Various colour spaces including ACESThe greatest innovation in colour space unification in a modern colour pipeline has been the ACES colour space. ACES offers a unified workflow for multiple modern cameras and sources while also operating at the very highest end of wide and modern Gamuts. In this class Charles explains the differences between various colour spaces and introduces the ACES colour space.
Class 9: ACES workflowWe continue our look at the high end and new ACES workflow. ACES is transforming major motion picture colour pipelines around the world. ACES is still very new and yet it has seen a huge take up by some of the best post houses and vfx companies in the world. In a sense, ACES is to colour what OpenEXR was to image files – a robust, serious format that takes some implementation but holds a bright future for solving many issues in implementing practical colour science.
Class 10: Why log coding is usedWe are all comfortable in taking about f-stops on set but people are less comfortable with logarithms, even given the close relationship between the two. In this class Charles shows the reason why log coding is used in image capturing and different data formats commonly used.