Color Mentor

In this episode I chat to Andrew Stockman and Andy Rider.
Andrew is the Steers Professor of Investigative Eye Research and Andy is a Senior Research Fellow in the same Institute of Ophthalmology at University College London.
They have been responsible for lots of the research into redefining the color matching functions for the standard human observer since the early 2000’s. The Luminous efficiency functions and then updating the LMS cone responses. 
Their work has formed the basis for the new standards adopted by the CIE, and has a lot of crossovers with the film industry and they regularly attend events discussing narrow band displays and observer metamerism failures. We chatted at length about the implications of their work.
I also had the pleasure of attending Andrew’s presentation at the AIC 2025 conference held in Taipei.
Andrew’s UCL website, where you can find the new CMF's:  http://www.cvrl.org/
We discuss:

(00:00) - Start.

(00:47) - Introduction.

(01:55) - Interview starts.

(03:02) - Updating the standard human observer.

(06:15) - Early cone research and standards.

(08:52) - Measuring photopigments.

(11:01) - Method of cone sensitivity measurement.

(14:30) - Color matching functions and conversions.

(15:11) - Narrow band primaries show errors in 1931CIE XYZ

(17:43) - Context and cognition.

(20:28) - Calibration and Individual differences.

(22:47) - Trichromacy and opponency.

(24:08) - Calculated luminance vs perceived brightness.

(27:50) - Vision as spatial information extraction.

(29:10) - Cone responses as a vital part of the cognition puzzle.

(30:40) - Negative values caused by matrix transforms.

(32:36) - Apple proposing color matching functions.

(36:36) - Multi primary displays.

(39:23) - LED Max multi band primary source.

(40:57) - Ratios of cone types and links to evolution and other species.

(42:15) - Eye vs camera differences.

(43:48) - Chasing wider gamut’s and metamerism failure.

(50:49) - Color matching functions the drive for rec 2020.

(53:23) - Variable primaries.

(55:41) - Comparing narrow and wide gamut, SDR and HDR.

(57:09) - LED Max and Maxwell’s method.

(01:00:01) - Fitting a models’ parameters to the measured data.

(01:01:40) - Maxwell’s method vs maximum saturation matching method.

(01:06:33) - Adding negative primaries while matching.

(01:07:54) - Soundness of Grassman’s additivity.

(01:09:53) - Proclivity for seeing patterns and geometric shapes.

(01:12:29) - Future research topics.

(01:13:57) - Genetic variations over time.

(01:16:39) - Many solutions to spatial perception.

(01:18:01) - Trichromacy through the ages.

(01:21:52) - End of the interview.

(01:22:12) - Andrew’s presentation at AIC 2025.

(01:42:08) - Outro.

(01:42:35) - End.

Check out   www.patreon.com/ColorMentor/    for colorist training and mentoring.

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In this episode I chat to Charles Poynton.
Many of you may know him as one of the foremost educators in our industry and he has had a formidable career. 
He is an independent contractor specializing in the physics, mathematics, engineering, and programming of digital colour imaging systems, including digital video, VFX/CGI, Digital Intermediate and digital cinema systems. He is involved in engineering wide colour gamut and high dynamic range systems. 
He does technology forecasting, systems modelling, algorithm development, 
video signal processing architecture, colour characterization 
and calibration and image quality assessment work. 
It was about 25 years ago that he decided that HD should have 1080 image rows, and square pixels.
He has been involved in developing many of the industry standards that we use today.
He wrote one of the most commonly used books for our industry titled: Digital Video and HD, Algorithms and Interfaces.
In December 2024 he hosted a Metamerism Experts Day, which was attended by a wide range of industry experts to discuss the various ways that metamerism is successful and how it fails more regularly with technological advancements.
We discuss the many complex topics presented at this event, and also his illustrious career.
Hope you enjoy it.
Charle’s website:   https://poynton.ca/
IMAGO article link:  https://imago.org/committees/technical/metamerism-experts-day-debrief/
Charles’s book:  https://www.amazon.com/Digital-Video-Second-Algorithms-Interfaces/dp/0123919266/
Color Mentor is on YouTube or your favorite podcast provider.

We discuss:

(00:00) - Start.

(00:53) - Introduction.

(02:46) - Interview starts.

(05:49) - Flanders and Barco in Belgium.

(07:39) - Charles’s history.

(09:31) - Sun Micro systems.

(10:24) - BT. 601.

(10:54) - Battle for 1080 lines and square pixels.

(20:35) - ICC development.

(21:44) - Transitioning to LCD monitors.

(23:31) - CRT monitors.

(25:31) - sRBG standard.

(27:09) - OETF’s and EOTF’s.

(43:16) - CRT’s spikey spectrums.

(45:19) - Metamerism experts day lead up. Bram and Steve.

(49:29) - Don’t call it RGB yet.

(51:30) - A quick history of color mixing and matching.

(53:24) - Illuminant metamerism.

(54:33) - Florescent bulbs and meat counters.

(56:22) - Observer metamerism.

(58:29) - Metamerism in virtual production.

(01:01:10) - Multi-primary systems.

(01:03:57) - Characterizing cameras.

(01:06:06) - Nudging primaries.

(01:14:06) - DLP and Xenon bulbs.

(01:18:57) - Personal color matching functions.

(01:22:01) - IMAGO article.

(01:22:21) - Mastering gamut’s.

(01:28:37) - Dynamics.

(01:32:25) - Apple EDR.

(01:35:49) - Cone fundamentals.

(01:43:47) - Rec 2020 as container not target gamut.

(01:48:31) - Problems of laser in cinema.

(01:53:10) - Outro.

(01:53:08) - End.

Check out   www.patreon.com/ColorMentor/    for colorist training and mentoring.

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This is the second of a two-part discussion I had with Richard Muller. He is a DIT based in Germany now, but like me started out in South Africa. He has a wealth of experience from working on shows like: Chappie, Avengers, Dark, Tribes of Europa, 1899, and more recently The Phoenician Scheme, where he was a virtual production supervisor.
We continue to discuss the testing and calibration of various film stocks for use on virtual studios. Also metadata and maintaining consistency and the challenges to doing good work when the D.I.T. role is not acknowledged. He has lots of great advice for people wanting to become D.I.T.s.
Richard’s Imdb:   https://www.imdb.com/name/nm3415527/
We discuss:

(00:00) - Intro.

(00:53) - Richard intro.

(01:35) - Interview starts.

(01:45) - Chappie.

(06:29) - Avengers.

(07:16) - Tribes of Europa.

(08:48) - Daylight reference library.

(10:51) - Metadata capture.

(11:34) - Shooting data analytics.

(12:58) - Scene-lapse continuity check.

(13:46) - Summary of a D.I.T’s role.

(14:21) - Watching everyone’s back.

(15:43) - Crew having their own equipment.

(18:49) - Cost of D.I.T equipment setup.

(20:13) - D.I.T and virtual production.

(23:10) - Understanding the signal chain.

(25:14) - Color managing textures in Unreal.

(27:52) - Characterizing lenses for virtual production.

(28:29) - La Comandante.

(31:46) - Big virtual studios vs small custom builds.

(35:54) - Developing the role of the D.I.T.

(38:59) - Learning paperwork structures.

(39:33) - Space for trainees.

(40:28) - Recce's and tests.

(41:29) - Perceived temporary nature of D.I.T’s.

(42:46) - Segmentation of roles and unions.

(44:33) - The need for flat dailies scans.

(47:11) - Spectral sensitivity and Ektachrome.

(50:45) - Profiling film stocks.

(51:30) - Initial Ektachrome tests.

(53:45) - Processing and scanning Ektachrome.

(55:57) - Shooting bracketed test charts.

(56:53) - IDT maker.

(59:03) - Comparing film scanners.

(01:00:44) - Open VPcal.

(01:01:55) - Choosing test steps.

(01:02:50) - Repeatability and who’s responsibility?

(01:05:59) - Creative play on top of wall calibration.

(01:08:54) - Moiré artifacts of film vs digital.

(01:11:14) - Spill light.

(01:13:59) - Automation and need for tests.

(01:17:36) - Expanding the role of the D.I.T.

(01:19:52) - Advice on how to become a D.I.T.

(01:29:08) - D.I.T and Cinematographers relationship.

(01:31:51) - Outro.

(01:32:19) - End.

Check out   www.patreon.com/ColorMentor/    for colorist training and mentoring.

★ Support this podcast on Patreon ★

This is the first of a two-part discussion I had with Richard Muller. He is a DIT based in Germany now, but like me started out in South Africa. He has a wealth of experience from working on shows like: Chappie, Avengers, Dark, Tribes of Europa , 1899, and more recently The Phoenician Scheme, where he was a virtual production supervisor.
We discuss the role of the Digital Imaging Technician and what in involves and also some testing he is doing with film and video acquisition combined with virtual studios. We discuss the quirks of various markets regarding the DIT.
Richard’s Imdb:   https://www.imdb.com/name/nm3415527/
We discuss:

(00:00) - Intro.

(00:53) - Richard intro.

(01:35) - Interview starts.

(02:40) - Working in South Africa and abroad.

(05:38) - Solutions for jobs.

(07:12) - Starting out.

(09:11) - Film vs digital exposure guidelines.

(10:25) - Post production experience.

(13:51) - Early digital cameras.

(15:47) - Is the role of the DIT easily defined?

(16:21) - Read the fucking manual.

(17:25) - LED walls, a complex color management task.

(22:26) - LED wall calibration.

(23:49) - Shooting tests on film.

(29:03) - Film scanners.

(32:33) - Color management and approaches to HDR.

(37:54) - Watching exposure.

(42:22) - Onset dailies grading.

(46:20) - Effect of a show LUT on production.

(52:32) - The many tasks of a DIT.

(56:47) - Backups and data security.

(01:02:58) - Q-take operator rather than DIT in Germany.

(01:08:17) - Cost saving of a DIT.

(01:09:50) - Reality shows and concerts.

(01:12:33) - Misconceptions about DIT’s.

(01:15:23) - Is the DIT part of the camera department?

(01:16:56) - Confidence booster.

(01:17:44) - Color pipeline collaboration.

(01:19:02) - Makeup artists.

(01:22:08) - The look of Dark.

(01:23:32) - Daniele’s look design talk for Filmlight.

(01:25:48) - Difficulty of grading on set.

(01:27:40) - Show LUT options and LUT’s of lore.

(01:29:48) - Outro.

(01:31:05) - End.

Check out   www.patreon.com/ColorMentor/    for colorist training and mentoring.

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In this episode I interview Menno Dreischor, a chemical engineer based in Amsterdam. 
His company TIPb offers engineering solutions for a wide range of industries. Menno’s interest in film led him to develop an algorithm to help with restoring the faded color on old film scans. It analyses the pixel distribution of a supplied source and target image and generates a matching LUT. It is currently in a beta testing phase and has many potential applications from restoration, shot matching and creative look design. He also has a second algorithm that tries to predict the aspects of an image that will induce visual cognition effects such as simultaneous contrast, assimilation and others effects. In the interview we discuss both projects and their potential applications.
Menno’s Color matching examples:
https://www.youtube.com/@colormatchinghub
We discuss:

(00:00) - Intro.

(00:53) - Menno introduction.

(02:51) - Interview starts.

(04:08) - Background in chemistry.

(05:29) - Connection to film.

(06:09) - Unofficial Star Wars restoration.

(08:46) - Matlab.

(10:25) - Drug analyzer.

(13:49) - Color Matching Project.

(15:30) - The matching process.

(16:45) - Histogram matching.

(21:12) - Theoretical basis.

(27:38) - Link to look design parameters.

(31:15) - Does it use machine learning?

(32:52) - Parameterization.

(40:54) - Entropy.

(48:26) - Open-source vs closed source.

(56:29) - Integration into current workflows.

(01:07:01) - Will this tool help or hinder creativity?

(01:13:34) - Over emphasis on matching.

(01:15:14) - Need for test footage.

(01:19:51) - Matching examples.

(01:31:39) - Visual cognition introduction.

(01:32:25) - The significance of cognition.

(01:33:47) - Does it affect the matching project?

(01:37:10) - How was it implemented?

(01:38:50) - Kernel based approach.

(01:40:50) - Assimilation's relation to resolution.

(01:42:21) - Visual cognition as a summary.

(01:47:14) - Matching is always done in context.

(01:48:46) - Uses of the cognition algorithm.

(01:53:41) - Discussion about compression and noise.

(01:55:41) - Screwball ideas on streaming.

(01:57:29) - Wrap up.

(01:59:58) - Outro.

(02:00:25) - End.

Check out   www.patreon.com/ColorMentor/    for colorist training and mentoring.

★ Support this podcast on Patreon ★