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made you look

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Cake day: July 27th, 2024

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  • WebP is the same, it’s got a lossy mode (VP8) and a lossless mode (Which is more limited than PNG, but beats it where it overlaps). But to make it more complicated the lossless mode also has lossy processing modes, where it alters the image first to achieve smaller output sizes.

    And PNG is no different.

    People have a long habit of turning JPEG files into PNG files, the file extension won’t help you there. They also could have reduced the colour depth or resized it, all lossy operations. All it really tells you is that it can have an alpha channel.

    As for AVIF, personally I don’t like the format, it feels like an “open media” (But still patented) version of HEIF to oppose Apple. Like WebP it makes the (baseless IMO) assumption that a format designed to encode motion data is better at encoding still data than a format designed to encode still data. It’s got all the limitations of a video format (It’s got a max resolution, only supports 12bit images, and no progressive decoding), and they left out all the enhancements from WebP (The dedicated lossless mode, “lossless AVIF” files are huge and the last I checked badly supported, so nobody actually used them, and they just called very high quality settings “lossless”)

    A team inside of Google was working on WebP2 around the same time, that used AV1 but actually added the useful stuff like efficient lossless encoding, it got killed too in favour of AVIF.


  • So it depends on the specific HDR encoding used, Rec2020 is the most common ones you’ll see (It’s meant for “pure” setups, i.e. where the source and output are tightly linked, e.g. gaming consoles or blu-ray, or so) and the raw data won’t look great. While something like HLG (Hybrid-Log Gamma) is designed for better fallback (As it’s meant for TV broadcast, where the output device is “whatever TV the user has”), so should just look dimmer.

    This is a HDR screenshot I took of Destiny 2, which uses Rec2020, tone mapped to SDR

    And here’s the raw screenshot data from before tonemapping.

    If the second image had all the right HDR metadata, and the viewer supported it properly, then both images would match.








  • I always thought it was purely a hardware limitation, but reading up on it I found it’s actually just “virtual 8086 mode” that was dropped, 16-bit protected mode is still available even when running the CPU in “long mode”.

    So it rules out DOS apps, but 16bit Win 3.x apps should still run. But it’s probably a compatibility minefield, and even MS decided it wasn’t important (iirc the only thing they kept around was support for 16-bit app installers, but by internally swapping them out with 32-bit versions when run, since it was apparently common for 32-bit 9x apps to still use 16-bit installers so they could show a proper error message when run under Win 3.x)