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   iced depresso (icedquinn@blob.cat)'s status on Monday, 25-Dec-2023 05:28:15 JST iced depresso
   > pixel differencing
   eh problem with these is that when it comes to compression, not all types of signal loss are valued equally.
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     iced depresso (icedquinn@blob.cat)'s status on Monday, 25-Dec-2023 05:30:50 JST iced depresso

     in reply to
     there was a jpeg optimization paper that noted about this. they use a geometric mean of like PSNR and SSIM or something. they also added a second pass over the block borders to include those blocky jpeg artifacts in the comparison.
     
     mostly cause PSNR only really evaluates color slopes well, and SSIM evaluates hard edges, and the human brain kind of does a bit of both. although things also get fucky because human eyes don't prioritize each color spectrum uniformly either. tis why a lot of old games had weird shit like 4 bit blues and 3 bit greens
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     iced depresso (icedquinn@blob.cat)'s status on Monday, 25-Dec-2023 06:14:23 JST iced depresso

     in reply to

     • gelato_al_pollo
     @gelato_al_pollo one example of "2 bytes per pixel" https://stackoverflow.com/questions/9972869/dxt4-texture-compression
     
     the color space of the RGB channels was sacrificed to drop the image size by 1/3rd, and one of the channels ends up with more precision than the others.
     
     similar stuff is done in audio. mp3 and opus are based on "psychoaccoustic" models where they basically make a computer model of how a human hears most sounds and then they re-prioritize the bits around the important bands.
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     gelato_al_pollo (gelato_al_pollo@puntarella.party)'s status on Monday, 25-Dec-2023 06:14:26 JST gelato_al_pollo

     in reply to

     @icedquinn
     I am curious now: can you share any pointer towards those games that had non uniform component sizes? Thanks in advance 😊