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Topics - Sebastian

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Raw Video / AXIOM looking for color science developer
« on: November 13, 2021, 12:39:56 PM »
We have recently made very exciting progress with uncompressed 12 bit 4k/UHD raw recording on the AXIOM Beta (entirely open hardware/free software high end camera community developed  project: https://www.apertus.org/axiom in case you have not heard of it before).
Its based on the experimental raw recording mode: https://www.apertus.org/axiom-beta-uhd-raw-mode-explained-article-may-2016 that we developed together with a1ex at the time - and it uses HDMI as "transport platform". The original approach turned out to be rather cumbersome to use though as recording devices altered the image in various ways (chroma subsampling, blurring, sharpening, compression) and a big part of the things we tried to do was reversing those steps to acquire the original raw data again - which was limited to 8 bits per channel at the time.

Now with the new approach we use a USB3 HDMI capture device which does not alter the image in any way and allows us to regain 12 bit raw directly as it arrives from the image sensor in the camera so all the above headaches are a thing of the past.
We still use a HDMI signal - pack our own custom pixel data into the video stream though. With some tuning we are even able to get non standard HDMI resolutions transferred (4096x2160, 4096x3072 - full image sensor resolution etc. at 24, 25 and 30fps). A1ex created a whole suite of conversion tools (https://github.com/apertus-open-source-cinema/misc-tools-utilities) and measurement routines to benchmark and analyse some aspects of the images and applied processing (darkframe subtraction, gainframe, non linear response compensation, clipframe and dynamic row noise compensation) but is currently not able to continue his work.

Here is a quick sample of recently captured footage with/without applied darkframe:

We are hoping to find someone interested in rebooting the color science work together with us and continuing building on top of the foundation that A1ex created.

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