"Photon Path" and "Glossary"

A new tool to understand and teach how a digital image is processed

par Philippe Ros Contre-Champ AFC n°344

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The "Photon Path" directly linked to the glossary has become a very helpful tool to communicate among committee members and has triggered the creation of an educational application. The Imago Technical Committee is happy to share this work in progress diagram for comment and contributions from the community. Arri, FilmLight, RED, and Sony have contributed to this scheme and the definitions linked to it. The ITC is in the process of obtaining approval from other manufacturers.

In 2020, the Imago Technical Committee (ITC), in cooperation with Charles Poynton, PhD, initiated a glossary to help clarify important cinematography-related terms in a concise and scientific manner. It was also decided that the glossary should be easy to comprehend, acknowledging that cinematographers, assistants, gaffers, DITs and colorists are not scientists or engineers.

As this task became increasingly complex, members realized that even among technically minded people, it was difficult to agree on all aspects of terms such as pixel, photosite, sensel, scene-referred, etc.

Daniele Siragusano (image engineer at FilmLight) started a simple sketch to draft the path a single photon would pass from light source through scene, lens, camera and post-production to the viewer looking at a display. As this sketch became very extensive, it helped understanding the order of signal processing and correct terminology in digital cinema.

This diagram is now linked to the glossary which is receiving new definitions.

Regarding the glossary, semantic problems are very present in international co-productions and/or post-productions that take place in several companies.

At the international Visual Media Lab Conference in Stuttgart in March 2023, David Stump, ASC, pointed out that in virtual production, these problems appear unexpectedly :
“Human beings can by effort overcome differences in language, semantics and syntax. We can discuss terminology and eventually move forward. However, when machines talk to other machines, there is no discussion of terminology. Without agreement on terminology, machines fail to communicate catastrophically”.
(Regarding this important conference a report will be shared by the Imago TC soon).


"Photon Path" & "Glossary"
In “View“, at the top of the window, please select : "Photon Path Detailed”

Diagramme du Chemin du Photon - 2

When clicking on a box, you can directly open the glossary, left side of the panel (see figure 3 below).

Diagramme du Chemin du Photon - 3

Each box has a specific color, for cinematographers and colorists, it is important to know that all the brown cases are related to creative processes. For DITs the deliverables cases are colored in green (see figure 4 below).

Diagramme du Chemin du Photon - 4

The low number of brown box colors underscores the fact that, for now, all these processes are driven by young technology, but that engineers are still exploring the creative possibilities of such a complex journey.
For some boxes, all process functions are detailed.
We can see at this step of “Signal Processing”, that many creative functions can be activated (see figure 5 below).

Diagramme du Chemin du Photon - 5

The Application of the Photon Path
Thanks to Professor Stefan Grandinetti, BVK, the ITC is currently working with students at the University of Applied Media Sciences in Stuttgart to develop an application of the "Photon Path".

The application is based on this glossary and diagram and aims to encourage all technicians to take an interest in this topic through an interactive and user-friendly experience.

The user will literally move through the diagram.

ITC - Projet de l’application du Chemin du Photon Path - 6

Under the supervision of Professor Simon Wiest and members of the ITC, the students have already started working. At the time of writing, the committee is already in its third weekly meeting with the students and the proposals and progress are very exciting.

File wrote by The Imago Technical Commitee

If you have any questions about this diagram, please contact :
itc chez imago.com