Poynton’s Vector – Tier 2

2026‑02‑03

Register at Circle.so.

A decade ago, I was contracted by SpectraCal, now Portrait Displays, to write a monthly 1000-word (2-page) note on a technical topic of my choosing. The series was called Poynton’s Vector; more information, and the issues themselves, are available.

I plan to renew the idea, at two levels. Tier 1, described elsewhere, is primarily for colourists and DITs at junior or intermediate level.

Tier 2, described here, offers all of Tier 1, plus more advanced information that requires more technical background and a higher level of math. The first Tier 2 technical document will be available to you Mon Mar 9, then every month thereafter. A 1-hour live web discussion will take place on Wednesday two weeks later, 18:00 Europe, 17:00 UK, 12:00 Eastern, 09:00 Pacific (and Thursday 04:00 in Sydney, sorry about that). Discussions about the month’s document can be addressed in the online session; we’re open to discussions of other topics. Video recordings will be available afterward for Tier 2 subscribers who cannot attend. Subscribers at Tier 2 will have access to an online discussion forum.

Graphs and equations will be shown and explained. If you have first-year university math: great! You’ll gain a deeper understanding of log coding, the CIE chromaticity diagram, and many other things. If you have high-school math, you’ll still follow, and you’ll increase your understanding of how math informs image and color science.

Topics in the queue for Tier 2:

  • What colour appearance phenomena are incorporated into ACES 2.0?

  • Metamerism: What happens when the spectral response of a camera, or the LMS visual response of a particular observer, departs from the colour matching functions of the CIE standard observer?

  • Photons-to-electrons: What physics lie behind the conversion of light to electrical signal in a modern cinema camera? What physical limits can’t be exceeded by any camera? Will cinema cameras ever have 16‑bit ADCs?

  • Sensitivity and exposure: What numerical relationships are involved in the definition of “ISO”? What’s “dual‑gain” in a sensor? What’s “dual‑ISO”?

  • Is the internet meme “The Dress” related to metamerism? (No.)

  • What is “photon noise”? Is it significant? (Hint: Yes.) Is photon noise related to dynamic range? (Hint: Surprisingly, no!)

  • Colour formation matrices: Why is “colour correction matrix” (CCM) almost always a misleading term? What are the noise consequences of a 3×3 matrix? Why was the Foveon sensor a commercial failure?

  • What is the significance of cinema camera colour primaries, or (x, y) coordinates of monochromatic stimuli, that lie outside the CIE 1931 (or 2015) spectral locus?

  • Why is “point-average gamma” a poor way to express the effective power function exponent of an EOTF? What’s a better method? (Hint: Nelder-Mead estimation.)

  • What is the origin of photochemical film’s S‑curve? Does print film emulation (PFE) involve just print film, or does it include the characteristics of the original camera negative (OCN)?

  • Some high-end cameras allow acquisition in PQ code. Is this a good idea? (No.) Should HLG at acquisition be called BBC‑log? (Yes.)

Subscribers at Tier 2 will have the opportunity to purchase a bound volume of masterclass handouts covering many of these topics, about 160 pages. Subscribers at Tier 2 will also be offered a 50% discount on any in-person workshop or masterclass that I present (except those organized by associations or societies over which I hold no sway).

Participants at Tier 2 might include:

  • experienced DITs

  • colourists and senior colourists

  • highly technical DoPs

  • studio colour scientists

  • display calibration technicians & engineers

  • graphics, video, and cinema software developers

  • visual effects (VFX/CGI) craftspeople & programmers

Tier 2 subscription is CAD 40/month, CAD 100/quarter, or CAD 360/yr. Over a year, you’ll get material roughly equivalent to a 1‑day masterclass (which on its own would have a registration fee of around CAD 400). These subscriptions are like magazine subscriptions: you start receiving issues when you subscribe. Back-issues of PDFs and video recordings will be available at a small fee.

Register at Circle.so. Issue 201 is available now; issue 202 will be available Mon Mar 16, with issues monthly thereafter.

Charles Poynton is an independent researcher and image/colour scientist based in Toronto. He wrote the book Digital Video and HD Algorithms and Interfaces, now in its second edition. Thirty five years ago, he chose 1080 image rows for HD standards, by which “square pixels” were established for HD and digital cinema. He earned his PhD in 2018 from Simon Fraser University with a dissertation entitled Colour Appearance Issues in Digital Video, HD/UHD, and D‑cinema. He is a Fellow of SMPTE, Colorist Society (CSI), and IMIS (formerly BKSTS). ∎