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Why Apple uses JPEG XL in the iPhone 16 and what it means for your photos

Apple 8 Comments

The iPhone 16 family has arrived and includes many new features, some of which Apple has played very close to its vest. One such improvement is the inclusion of JPEG XL file types, which promise improved image quality compared to standard JPEG files while delivering relatively smaller file sizes.

[…]

Overall, JPEG XL addresses many of JPEG’s shortcomings. The 30-year-old format is not very efficient, only offers eight-bit color depth, doesn’t support HDR, doesn’t do alpha transparency, doesn’t support animations, doesn’t support multiple layers, includes compression artifacts, and exhibits banding and visual noise. JPEG XL tackles these issues, and unlike WebP and AVIF formats, which each have some noteworthy benefits too, JPEG XL has been built from the ground up with still images in mind.

↫ Jeremy Gray at PetaPixel

Excellent news, and it will hopefully mean others will follow – something that tends to happen when Apple finally supports to the new thing.

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Thom Holwerda

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8 Comments

  1. 2024-09-20 4:28 pm
    Adurbe

    My hotos? How rude.

  2. 2024-09-20 5:07 pm
    ssokolow (Hey, OSNews, U2F/WebAuthn is broken on Firefox!)

    Unfortunately, JPEG XL introduced a regression… it supports animations.

    Yet another format where, if I support it, I’m going to need to run a sandboxed image parser in situations like “select the image to use as your avatar” to strip out later frames, and my file manager needs more than a simple magic number match to determine what kind of file I’m dealing with.

    At least APNG is a flat-out violation of the PNG spec, which is why the reference implementation will never support it. (The PNG spec explicitly says that the PNG header denotes that all images in the PNG file will be derived from a single abstract image, and the rationale document associated with the PNG spec explicitly says they thought Animated GIF was a mistake.)

    The first eight bytes of a PNG datastream always contain the following (decimal) values:

    137 80 78 71 13 10 26 10
    This signature indicates that the remainder of the datastream contains a single PNG image, consisting of a series of chunks beginning with an IHDR chunk and ending with an IEND chunk.

    — https://www.w3.org/TR/PNG/#5DataRep

    b. The reference image, which only exists conceptually, is a rectangular array of rectangular pixels, all having the same width and height, and all containing the same number of unsigned integer samples, either three (red, green, blue) or four (red, green, blue, alpha). […]

    c. The PNG image is obtained from the reference image by a series of transformations: alpha separation, indexing, RGB merging, alpha compaction, and sample depth scaling. […]

    — https://www.w3.org/TR/PNG/#4Concepts.Sourceimage

    PNG also does not support multiple images in one file. This restriction is a reflection of the reality that many applications do not need and will not support multiple images per file. In any case, single images are a fundamentally different sort of object from sequences of images. Rather than make false promises of interchangeability, we have drawn a clear distinction between single-image and multi-image formats. PNG is a single-image format.

    — https://www.w3.org/TR/PNG-Rationale.html

    • 2024-09-21 2:23 am
      sukru Silver Supporter

      ssokolow,

      I think animations are a side product of having multiple layers:

      There can be multiple frames, with non-zero duration (for animation) or with zero duration (making them work more like layers in graphics software). Frames can be smaller or larger than the image canvas and can be blended in various ways. However, regular video codecs are still preferred for encoding realistic content.

      From https://en.wikipedia.org/wiki/JPEG_XL

      Basically someone would eventually hack this into the format in a non-standard way. It is too tempting to use multiple images (which were supposed to be layers) in a succession as animations. So they took the preemptive step and included that as standard.

      But of course I might be misreading this.

  3. 2024-09-20 5:31 pm
    jgfenix

    But is it better than JPEG 2000? Now that the patents have expired…

  4. 2024-09-20 6:51 pm
    kurkosdr

    The good news is that, unlike HEIF/HEIC, JPEG XL is royalty-free, which is a nice surprise.

    Since HDR will break compatibility with most JPEG implementations out there anyway, why not embrace a state-of-the-art royalty-free format?

    • 2024-09-21 2:26 am
      sukru Silver Supporter

      kurkosdr,

      And I don’t understand why Google does not support it.

      This random site for example (really random, just Googled for an example, … ah the irony):
      https://jpegxl.info/old/art/

      Does not render correctly in Chrome.

      They used to champion open formats, so much so that they developed their own for video ones (and also bought an existing company).

  5. 2024-09-20 9:51 pm
    andrenext

    good step for a faster general adoption, avif is very good too, both are way better than webp, which I really dislike..

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