silvan schnelli Posted April 7 Share Posted April 7 I downloaded 5213 35 film scan DPX footage and ARRI XT footage from https://www.cinematography.net/Valvula/valvula-2014.html. My goal is to compare the footages and put them through a post pipeline that I am amending and tinkering with. However, when I loaded the two DPX files into Nuke, I noticed that the film scan is much darker and slightly more contrasty than the Alexa footage. I then applied a OCIOFileTransform to both, a LogC2 to rec709 conversion for the alexa and davincis Kodak 2383 PFE for the film scan. The colours look great but the film scan is much more underexposed. On the CML website the footage looks relatively the same exposed, but for me the film looks much more underexposed. What am I doing wrong or misinterpreting? ARRI XT (16bit) with classic LogC2 to rec709 and Kodak Film with Davinci 2383 PFE 1 Link to comment Share on other sites More sharing options...
Site Sponsor Robert Houllahan Posted April 10 Site Sponsor Share Posted April 10 On 4/7/2024 at 8:09 AM, silvan schnelli said: I downloaded 5213 35 film scan DPX footage and ARRI XT footage from https://www.cinematography.net/Valvula/valvula-2014.html. My goal is to compare the footages and put them through a post pipeline that I am amending and tinkering with. However, when I loaded the two DPX files into Nuke, I noticed that the film scan is much darker and slightly more contrasty than the Alexa footage. I then applied a OCIOFileTransform to both, a LogC2 to rec709 conversion for the alexa and davincis Kodak 2383 PFE for the film scan. The colours look great but the film scan is much more underexposed. On the CML website the footage looks relatively the same exposed, but for me the film looks much more underexposed. What am I doing wrong or misinterpreting? ARRI XT (16bit) with classic LogC2 to rec709 and Kodak Film with Davinci 2383 PFE 16bit DPX is linear not LOG. 1 1 Link to comment Share on other sites More sharing options...
silvan schnelli Posted April 11 Author Share Posted April 11 (edited) @Robert Houllahan Thank you for the simple and quick reply. It is something I only realized later through trial and error. Nevertheless, for some reason the footage still appears a bit off, but changing from log to linear fixed the issue for other film footage I have downloaded. Edited April 11 by silvan schnelli Link to comment Share on other sites More sharing options...
Site Sponsor Robert Houllahan Posted April 15 Site Sponsor Share Posted April 15 Cineon LOG is a kind of lossless compression designed by Kodak to follow the characteristic curve of how negative film works, so the density range could be put into 10 bits. All digital sensors are linear response and early Cineon and Quantel scanners used Kodak tri-linear (RGB LIne) CCDs which were 12bit or 14bit linear, the Arriscan is a 14bit ALEV sensor and 2-flash gets it to 16bit precision. So all LOG curve schemes have followed on from the Cineon LOG designed by kodak in the late 1980's There is still calibrating the scanner to the film base and both exposure and lab variations and I think there is no way to just add technical and look LUTs to get a perfect image without also doing some base grading. Link to comment Share on other sites More sharing options...
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