Frank Olean Posted May 4, 2022 Share Posted May 4, 2022 If I shot with HD cameras at a native 1.78:1 ratio (1920x1080), how should I crop to… 1.85:1? 2.39:1? On blu-rays I find different values and I don't know why. For example, with 1.85:1 I see black bars on the top and bottom with 22 pixels each (1920x1036) and with 20 pixels each (1920x1040). But on UHD blu-rays I always see the same thing, bars on the top and bottom with 42 pixels each (3840x2076). In the case of 2.39:1 something curious happens. Most blu-rays are 2.40:1 instead of 2.39:1, that is, black bars on the top and bottom with 140 pixels each (1920x800). I find 2.39:1 (1920x804), and black bars on the top and bottom with 138 pixels each, on rare occasions. What is the correct pixel value? 22, 20? 140, 138? Link to comment Share on other sites More sharing options...
Nicolas POISSON Posted May 5, 2022 Share Posted May 5, 2022 Based on calculus, 1.85 format cropped into FullHD should be displayed as 1920x1038, with 21 pixels black bars on top and bottom. I read somewhere that the resolution shall be a multiple of 4, although I do not know why (maybe linked to the macro-blocks of the compression algorithms ?). Starting from 1038, the closest multiples of 4 are 1036 or 1040, which leads to black bars of 20 or 22 pixels height. Maybe the variation you see is just different people choosing different closest multiple ? Doubling the resolution, the problem does not exist any more: 2076 is a multiple of 4 so the exact height of 42 is acceptable. 1 Link to comment Share on other sites More sharing options...
Frank Olean Posted May 15, 2022 Author Share Posted May 15, 2022 (edited) Thank you very much for this information, Nicolas. Edited May 15, 2022 by Frank Olean Link to comment Share on other sites More sharing options...
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