Is it possible to upscale a 1920x1080 video (lossy h264@20000kbit/s, recorded with shadowplay) to 3840x2160 without any quality loss from upscaling the video so that 1 pixel becomes a square of 4?
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1Of course it's possible. – szatmary Jun 25 '16 at 22:33
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@szatmary Without *any quality loss*? – Gyan Jun 26 '16 at 10:37
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1Sure. Unless you then encode it with a lossy codec after you scale. But your question did not include that. – szatmary Jun 26 '16 at 11:05
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@szatmary sorry should have added that from the beginning. Edited! – Atemu Jun 26 '16 at 20:16
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1I think the OP means sharpness (basically the Hollywood/CSI "enhance" effect). – Gyan Jun 26 '16 at 20:46
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I wanted to upscale my video files to 4x the resolution where 1 pixel would become a square of 4 pixels, so that I don't get the rest of the pixels calculated in. I don't really know what you mean by the ""enhance" effect". – Atemu Sep 27 '16 at 20:59
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Upscaling itself does not induce any quality/information loss, it is the encoding step. Assuming the below steps you are -probably- intending to do:
h264 encoded video
-1-> auto. converted to raw video/representation in editor
-2-> upscaling to 2x
-3-> re-encoding(saving) back to h264.
The only step that results in -irreversible- quality loss is 3. The quality/information in all other steps are the same and the result will be very similar to the one in step 1, with some (more) information loss...
Assuming the viewer's browser can use advanced methods in upscaling/downscaling the video (almost all modern ones can), there is no need to change the resolution; no new information is added to the input so no quality gain will be acquired.
user3648895
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ok is it possible to remove all quality loss from the upscaling somehow? – Atemu Jun 26 '16 at 20:17
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3/4 of the new image' pixels have to be "generated" which is an irreversible step unless you upscale with nearest neighbor interpolation by a factor which's square root is a natural number. – Atemu Jan 04 '17 at 17:53
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How do browsers relate to this? It's my understanding that if a video is uploaded in a certain resolution that's the maximum resolution it can be selected to be played at in YouTube's player. It wouldn't really make sense for browsers to interfere with that and silently upscale to 4k when the maximum resolution that YouTube allows the user to switch to is 1080p, for example. – Hashim Aziz Oct 17 '21 at 22:25