Recording and presentations of:
November 3, 2022, AMPAS / ITC Seminar
”Evaluating LED Lighting for Cinematography Using SSI (Spectral Similarity Index)”
At a time when the use of LEDs and their evaluation are becoming paramount, the Academy of Motion Picture Arts and Sciences and the IMAGO TC (ITC) are pleased to share this event.
In the world of cinematography, LEDs can no longer be measured by CRI, TLCI, or TM-30 lighting metrics. The SSI metric is opening a new and effective way to evaluate LED lighting. This seminar shares information, discussions, and debate on this topic.
Please find:
- The recording of the seminar (1) and the exchanges (2) of the participants and panelists in the chat
- The core of this seminar (3): the presentation by George Joblove (Senior Director, Technology and Standards, Academy of Motion Picture Arts and Sciences Science and Technology Council): ”SSI, An Introduction to the Spectral Similarity Index (SMPTE ST 2122)”
- The presentations of:
- John Christian Rosenlund (4), Cinematographer, FNF
- Felix Hüsken (5), BVK, CSI Senior Colorist, Display Calibrator & Consultant
- Philippe Ros (6), Cinematographer, AFC, ITC co-chair: excerpt from the ”Conference of light”
- Tim S Kang (7), Cinematographer, ASC associate member
- The resume of all the panelists
- The ”Conference of light” full version: https://www.lcauk.com/fr/2020/02/26/conference-of-light/
Tests made by Michael Carstens, Head of Cinematography Dept Delight Rental Services, Berlin, Timm Brückner, Gaffer, Berlin, Matthias Fleischer BVK Cinematographer, Tobias Wiedmer, Colorist, CineChromatix & Nick Shapley, Founder & Managing Director LCA: Lights Camera Action with the help of Philippe Ros, AFC and Dirk Meier, colorist, BVK CSI.
- The CML tests on LEDs: https://cinematography.net/LED-Camera/LED-Camera-Index.html
These evaluations were supervised by Adam Wilt and Geoff Boyle in February 2020 at the Netherlands Film Akademie studios in Amsterdam with the invaluable assistance of Camalot and Vocas. Organized by Mick Van Rossum NSC. With the help of Cinematographer Marina Kissopoulos AC/DIT Erik Weidenhof.
The recording of the seminar (1):
The exchanges (2) of the participants and panelists in the chat:
01:27:26 Aleksej Berkovic, IMAGO TC: Please post your questions here
01:27:41 patrick DUROUX: i am a basic Dop Patrick / regarding LED what about polarisation ?
01:28:55 Jan Klier - Colorist/Finishing Artist: So SSI computes the volume difference of the two curves. As noted the camera sensitivity is not linear either. Would there be a useful variation of SSI that computes the difference between all three variables, some of which may cancel out or amplify. That could capture not just quality of light, but light & camera combination.
01:32:18 Jan Klier - Colorist/Finishing Artist: Second question - does SSI only capture the overall similarity but not if it's localized or broad, which may matter.
01:42:54 Daniele Siragusano (FilmLight): For after the Coffee Brake: what are the pros and cons between SSI and TM-30-15?
01:50:28 Daniele Siragusano (FilmLight): Thanks Alex, Is then the contrary also true, a low SSI value might not mean that a certain object behave differently under the illuminant and ref illuminant?
01:51:23 Daniele Siragusano (FilmLight): So SSI is more “overall” . Generally the chance to get different rendering is higher with low SSI value.
01:53:13 Alex Forsythe (The Academy): Yes, that is generally expected to be true. If the SSI is low, we would expect an observer (camera or human) to react very differently to a given object lit by the low SSI source.
01:53:36 Aleksej Berkovic, IMAGO TC: Dear Jan, thank you for a question! It is a very good one and will be answered shortly!
01:55:13 Alex Forsythe (The Academy): Again, testing is key as there's pathological cases where low SSI lights may produce very close results to a reference source, but the user of the sources should be aware there may be problems.
01:56:17 Marc Galerne K5600: If I understand well: Dealing with Leds and DIgital cameras is like marriage: it's trying to solve new problems that we didn't have before. :)
01:56:40 Alex Forsythe (The Academy): ?
02:01:34 Jan Klier - Colorist/Finishing Artist: There is a long history in calibrating reference monitors and keeping them in tight tolerances in total and over lifetime. That same could be applied and/or needed to actual fixtures (this is re: Uwe's description).
02:20:15 Nils de Montgrand - Rosco DMG: Daniele type your question !
02:20:27 Daniele Siragusano (FilmLight): Was more a comment ;-)
02:27:56 Dirk Meier BVK CSI - Colorist: @Tim, would you share your presentation? Very nicely illustrated and I’d love to dig deeper.
02:28:21 Tim S. Kang: yes, how can I share?
02:30:57 David Baud, csi: Uncompressed vs compression? Another Analogy?
02:31:37 Dirk Meier BVK CSI - Colorist: Luke could just upload it here in the chat e.g.
02:32:57 Luke Crawford (The Academy): Here is Tim's presentation!
02:33:11 Dirk Meier BVK CSI - Colorist: Great, thank you very much!
02:33:41 Edi Walger: Thanks for the doc!
02:34:36 Alfonso Parra AEC, ADFC/IMAGO ITC: Thanks
02:35:35 Jan Klier - Colorist/Finishing Artist: There have always been products for the discerning minority and more value oriented majority. As content has exploded in volume the economics shift by necessity.
02:38:17 Philippe Ros AFC / ITC Co-chair: Thanks Tim!
02:50:34 Marc Galerne K5600: And full Spectrum for All
02:50:53 Stefan Grandinetti BVK/ITC: Thanx for the great seminar - good bye everybody!
02:51:21 Alex Forsythe (The Academy): Acescentral.com
02:51:26 patrick DUROUX: thank you for your imput and informations ! amities, Patrick
02:51:27 Ricardo Matamoros SVC: Thanks to all
02:51:30 David Baud, csi: Thank you all for a great pane
