Color Mentor

By Paul HanrahanTV & Film Arts Film Interviews Visual Arts

Color Mentor episodes

March 28Interview with Andrew Stockman and Andy Rider.
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.
★ Support this podcast on Patreon ★
1 hr 43 min
January 31Charles Poynton Interview.
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.
★ Support this podcast on Patreon ★
1 hr 54 min
October 13, 2025Interview with Richard Muller - Part 2
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 ★
1 hr 33 min
September 28, 2025Interview with Richard Muller - Part 1
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.
★ Support this podcast on Patreon ★
1 hr 32 min
April 16, 2025Interview with Menno Dreischor
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 ★
2 hr 1 min
March 03, 2025Interview with Akiyoshi Kitaoka
In this episode I relate a written interview I had with Dr. Akiyoshi Kitaoka, a Professor of Psychology based in Japan. He does research on visual perception and makes visual illusions. His work embodies a fascinating combination of creative and technical aspects. I’d recommend viewing this episode on YouTube rather than as an audio podcast as there are many visual demonstrations.
Color Mentor is on YouTube or your favorite podcast provider.
Dr. Kitaoka’s website:
https://www.ritsumei.ac.jp/~akitaoka/index-e.html

We discuss:
(00:00) - Intro.
(00:53) - Introduction to Dr. Kitaoka.
(03:45) - His teachers.
(05:32) - His research.
(07:37) - Color space visualizations.
(10:33) - HCV Color model.
(15:51) - Chromostereopsis.
(16:59) - Reproducibility.
(17:34) - Ostwald color model.
(20:19) - Screen printing.
(22:10) - Color mixing.
(23:22) - Screen printing project.
(29:08) - Color constancy.
(30:55) - Monge.
(33:45) - Reduced gamuts.
(35:53) - Histogram manipulations.
(37:25) - Image creation.
(39:28) - Vection.
(41:17) - Illusory colors.
(44:31) - Translucency and transparency.
(46:18) - Maxwell's spot.
(48:17) - Additive and subtractive systems.
(01:00:18) - Pixel grids.
(01:04:39) - Faces.
(01:09:26) - Plans for the future.
(01:09:58) - Treasures on his website.
(01:12:17) - Outro.
(01:12:45) - End.

Check out www.patreon.com/ColorMentor/ for colorist training and mentoring.
★ Support this podcast on Patreon ★
1 hr 13 min
November 28, 2024Interview with Kevin Shaw - Part 2
In this second part of the interview with Kevin Shaw I talk to him about the Colorist Society, and around the drive for our industry to organize itself in general. We talk about local and global issues, trade unions, recognition and awards, development and training and much more. I’m keen to hear your experiences with industry organization attempts in the past, let me know in the comments.
Here is the IMDB petition if you would like to add your comment:
https://community-imdb.sprinklr.com/conversations/data-issues-policy-discussions/could-we-please-have-a-separate-colorist-department/5f4a7a328815453dba9d9d1a

We discuss:
(00:00) - Intro.
(00:48) - List of Issues.
(02:04) - Facing your competitors.
(02:37) - Members benefits.
(03:18) - Formal or informal?
(03:49) - Running Costs.
(04:41) - Local and Global.
(05:25) - Production Optimization.
(06:22) - Development and Training.
(07:11) - Mentorships.
(07:30) - Silos in Production.
(08:34) - Recognition and awards.
(08:57) - Industry Personalities.
(09:26) - Transparency and governance.
(09:44) - Efficiency and decision making.
(10:05) - Become a trade union?
(11:00) - Standardizing rates.
(13:28) - Organization process.
(13:53) - Film Funding.
(15:43) - Copyright.
(15:59) - Legal Assistance.
(16:18) - SAFAITS case study.
(17:46) - Interview starts.
(18:02) - The need to organize.
(19:10) - Educating clients.
(19:44) - Not represented, not recognized.
(20:29) - Colorists on panels.
(22:29) - Choosing a name.
(25:10) - Who do you call?
(26:35) - Film credits.
(28:39) - Colorist mixer.
(29:38) - Filmlight Awards.
(30:43) - Colorists and Cinematographers.
(32:41) - Organize yourself.
(34:27) - Needs of different markets.
(36:52) - Stabilizing prices.
(39:45) - Many challenges.
(42:32) - Proving a platform.
(43:50) - Making connections.
(45:22) - How far have we come?
(48:34) - Sustainability.
(50:48) - IMDB Petition.
(55:36) - Color Department.
(58:13) - The last touch.
(01:01:35) - Need for more awareness.
(01:06:27) - Accreditation.
(01:13:25) - Colorist test.
(01:17:18) - Outro.
(01:17:45) - End.

Check out www.patreon.com/ColorMentor/ for colorist training.
★ Support this podcast on Patreon ★
1 hr 18 min
October 30, 2024Interview with Kevin Shaw - Part 1
In this episode I chat to Kevin Shaw. He is a well know colorist and educator in our industry.
He has also been a key figure in setting up and promoting the Colorist Society, which is the topic of our following episode. In this episode however we discuss telecines. Kevin started grading 10 years before I did, at a time when color grading was either telecine or film lab based. We discuss various stages that the industry has gone through since then, all the way up to the present.
We discuss:
(00:00) - Intro.
(00:48) - Introduction to Kevin and telecines.
(02:39) - Interview starts.
(04:37) - Telecine engineers.
(06:30) - Music videos.
(07:34) - Study.
(11:11) - Telecine Limited.
(12:15) - Analog Davinci.
(13:13) - One new feature per year.
(13:43) - Davinci product demos.
(14:08) - No freelancers.
(14:53) - What is a telecine?
(17:24) - Blue Moon.
(17:45) - Tape playouts.
(18:44) - Facility life.
(21:00) - Abekus and frame store.
(23:12) - Long hours.
(24:21) - Tools.
(27:55) - Picture encoding.
(29:12) - God monitor.
(33:21) - Titles and finishing.
(35:01) - Low contrast prints.
(36:45) - Telecine as loss leader.
(42:55) - Show it on the wall.
(44:02) - Quality vs convenience tradeoff.
(48:21) - Taller gamut volumes.
(52:12) - Film restoration.
(57:07) - Software color correction systems.
(01:01:02) - Film lab profiles.
(01:05:01) - S curve and other tools.
(01:06:08) - Introduction of log spaces.
(01:10:38) - ACES archives.
(01:17:01) - Rocket science.
(01:20:45) - Art need limitations.
(01:23:10) - Bezier envy.
(01:23:38) - Tastes and trends.
(01:32:06) - User manuals.
(01:34:19) - Telecine calibration.
(01:40:16) - Scopes and visualization.
(01:45:21) - Technical vs creative transforms.
(01:49:43) - Skin and tone curves.
(01:51:24) - Hue vs Lum.
(01:53:41) - Unorthodox telecine techniques.
(02:00:45) - Psychology and resetting.
(02:05:17) - Grading suite dynamics.
(02:15:05) - Evolution of new tools.
(02:16:39) - Linking pre and post.
(02:20:06) - HDR monitors on set.
(02:21:07) - Recent work.
(02:26:00) - QD OLED and HDR.
(02:29:34) - Future of HDR.
(02:35:03) - HDR in cinema.
(02:39:04) - Hole punches and punch tape.
(02:42:45) - Outro.
(02:43:12) - End.

Check out www.patreon.com/ColorMentor/ for colorist training.
★ Support this podcast on Patreon ★
2 hr 44 min
October 14, 2024Interview with Troy Sobotka - Part 2
This episode is the second part of my conversation with Troy Sobotka who is a Vancouver based lighting, rendering and all-round image creation person. You may know him as the designer of the Agx render transform. We dive further into the mechanisms of visual cognition and picture formation. He shares a vast knowledge and collection of reference material on this topic. See download link below for additional material.

In past years he has written an online blog called the Hitchhikers Guide to Digital Color. I would highly recommend people to read it.
We discuss:
(00:00) - Intro.
(01:11) - Episode summary.
(01:43) - Visual examples of phenomena.
(01:59) - Light and shade.
(03:57) - Gilchrest’s gamut compression.
(05:51) - Simultaneous contrast.
(06:21) - Shimmer / luster.
(07:26) - Induced contrast.
(08:06) - Glare halo.
(08:31) - Hermann grid.
(08:57) - Watercolor effect.
(10:31) - “Chevreul Effect”.
(10:57) - Crispening.
(11:46) - Neon Color Spreading.
(12:18) - Chromatic induction.
(12:46) - Gamut Compression/Expansion.
(13:18) - Chromostereopsis.
(14:11) - Face vase, Rabbit duck, Necker Cube.
(15:39) - Kanizsa triangle.
(15:57) - Dr. Tse cognition examples.
(17:54) - Not the pixel you thought you saw.
(18:45) - Pictorial exposure.
(20:37) - Gain and offset dimensions.
(21:47) - Image examples.
(24:47) - Decomposition framework.
(26:54) - Newtonian physics metaphor.
(29:20) - Interview starts, stimuli are not color.
(34:43) - It’s all constructed. Dr. Hoffman interface.
(36:56) - What is pictorial exposure?
(42:12) - Correlated signals “luminance” and “chrominance”.
(47:28) - Colorimetry’s limitations.
(56:38) - The domain of Metrics.
(01:05:22) - The domain of Stimuli.
(01:07:21) - The domain of Cognition.
(01:08:32) - Three broad Mechanisms of cognition.
(01:09:28) - Current predicament of image makers.
(01:18:31) - Increment and decrement signals.
(01:23:48) - Gain regulation.
(01:27:46) - SDR vs HDR.
(01:32:19) - Field propagation.
(01:34:47) - Can output transforms be dynamic?
(01:37:36) - Three Cognitive processes.
(01:38:53) - Form decomposition.
(01:44:47) - Why is the canvas flat?
(01:46:47) - Form computation.
(01:48:26) - Form assignment.
(01:52:59) - Towards practical examples.
(01:57:12) - Gain and offset dimensions.
(02:05:03) - Cognition limits.
(02:07:43) - Leading the eye.
(02:08:54) - Brand colors, vanta red.
(02:10:41) - Example of gain and offset.
(02:13:05) - Why not just desat to white?
(02:15:25) - Some history of picture formation.
(02:16:31) - Versioning.
(02:22:17) - Look creation and display transforms.
(02:27:48) - Ergonomics.
(02:35:35) - Bigger, better, faster.
(02:42:00) - Outro.
(02:41:33) - End.

Download link for additional images and pre interview discussions:
https://www.dropbox.com/scl/fi/2o8hwqfyx9lc42dobysjg/EP0006_TROY-SOBOKTA_PART_2.zip?rlkey=jpi8ol0tnivqyugv3p6varx02&dl=0
Check out www.patreon.com/ColorMentor/ for colorist training.
★ Support this podcast on Patreon ★
2 hr 42 min
September 26, 2024 Interview with Troy Sobotka - Part 1
In this episode, I chat to Troy Sobotka who is a Vancouver based lighting, rendering and all-round image creation person. You may know him as the designer of the Agx render transform. We discuss the topic of Visual Cognition as it relates to how we make pictures. He shares a vast knowledge and collection of reference material on this topic.

In past years he has written an online blog called the Hitchhikers Guide to Digital Color. I would highly recommend people to read it.
We discuss:

Download link for additional images and pre interview discussions:
https://www.dropbox.com/scl/fi/jaute657ixv9sfw9cyh3y/EP0005_TROY-SOBOKTA_PART_1.zip?rlkey=1q4v43fg59d1kbkfoj6vxr1pm&dl=0
Check out www.patreon.com/ColorMentor/ for colorist training.
★ Support this podcast on Patreon ★
1 hr 58 min

About Color Mentor

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Paul hanrahan interviews film industry professionals about the art and science behind color grading and image making in general.

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