4 ms·

That doesn’t seem like a great reason to use JPEG XL. Existing JPEGs are meeting the needs of their users. Sure, maybe those images could be ever more compresse

by maria2 4y ago

That doesn’t seem like a great reason to use JPEG XL. Existing JPEGs are meeting the needs of their users. Sure, maybe those images could be ever more compressed, but it’s clearly not a deal breaker otherwise those images wouldn’t have been JPEG encoded in the first place. Second, the amount of existing JPEGs [that people care about] will decrease over time, both in quantity and as a portion of the total image population. So lossless re-encoding is a solution in search of a problem.

mort96 4y ago
Over the past 30 years, JPEG has been the best generally available compression format, and it's what consumer cameras generally use to store their photos. I'm not sure what you imagine people would have used instead if storing images efficiently is "a deal breaker". As for the amount of existing JPEGs that people care about decreasing over time: This might eventually become true, but only to a point. People's existing photo archives are generally all JPEGs. People care about even (especially?) the older images in their photo albums. And it will take a long time before everyone is adding exclusively AVIF-encoded rather than JPEG-encoded images to their archives.
- maria2 4y ago
  Does re-encoding JPEGs as JPEG XL really unlock anything new? The answer is likely no. So this case is not useful to optimize for. As for people's photo albums. The iPhone is already storing new images in HEIF, so JPEGs are becoming less relevant with each passing day. And of course, you can still view the old images perfectly fine as JPEGs.
  - mort96 4y ago
    I don't know what you mean by "unlocking anything new". You have identical images at a smaller size. Old images in your photo library aren't becoming less relevant with each passing day. I don't know why you would suggest that they are. I know that iPhone has switched to storing images as HEIF and nothing in my comment suggested otherwise.
    - maria2 4y ago
      > I don't know what you mean by "unlocking anything new". You have identical images at a smaller size. Yes exactly, nothing new is unlocked. So why would I use this format? Was the old size of the images preventing me from enjoying them in any way? No. Of all the old JPEGs out there that absolutely must be losslessly transcoded from the already lossy JPEG encoding, how many are prohibitively large? You can still look at both a JPEG and JPEG XL image locally. Most likely you'd be able to serve both images over HTTP, although the JPEG image may take a bit longer to load. And how many cases require the new and old images be exactly the same? My point is that, if the main selling point of your codec is that you can create the same thing as 30 years ago only smaller, then it's going to be a hard sell compared to other formats out there. If the choice was between JPEG and JPEG XL, then sure, let's use JPEG XL. But the choice is between JPEG XL and other formats with better features. Other image formats like AVIF add new features that enhance images. Yes, the images are smaller, but also way more powerful. Image sequences, for instance, enable new features like "live images." Converting your old JPEG to a smaller JPEG isn't going to magically enable live images. tldr: I'm looking for a reason to care that I can losslessly re-transcode my old JPEGs. Ok, the re-transcoded images are smaller and exactly the same as before, but what is a real world reason why I would need that vs. using the old JPEG directly or re-transcoding it to AVIF?
      - mort96 4y ago
        > So why would I use this format? Because the size is smaller and the quality is the same? Literally the same reason why you'd use any new image format, except that this benefit also applies to existing images, not just new ones? I'm not against AVIF or anything, if you want to add future images which are using fancy animation features from AVIF then that's cool. You don't have to choose between image formats, you can (and already do!) use the right one for the task. > tldr: I'm looking for a reason to care that I can losslessly re-transcode my old JPEGs. Ok, the re-transcoded images are smaller and exactly the same as before, but what is a real world reason why I would need that vs. using the old JPEG directly or re-transcoding it to AVIF? You can use the old JPEG directly, but then your library takes up more space. If you re-transcode your old JPEGs to AVIF, you're losing quality or at the very least irreversibly changing the images. I'm not arguing that it's the world's biggest deal or anything, but a free 20% size reduction on all photos in an image library and all JPEGs sent over the web doesn't seem like a bad deal.
lifthrasiir 4y ago
Individual features of JPEG XL might be not enough, but JPEG XL is a package for all those features, which make it much more attractive than alternatives. And JPEG is really popular while WebP, which finally reached a point of universal support recently, still struggles [1]; it will remain popular enough for at least a decade and probably more. [1] https://w3techs.com/technologies/overview/image_format https://w3techs.com/technologies/overview/image_format

by maria2 4y ago

mort96 4y ago

Over the past 30 years, JPEG has been the best generally available compression format, and it's what consumer cameras generally use to store their photos. I'm not sure what you imagine people would have used instead if storing images efficiently is "a deal breaker". As for the amount of existing JPEGs that people care about decreasing over time: This might eventually become true, but only to a point. People's existing photo archives are generally all JPEGs. People care about even (especially?) the older images in their photo albums. And it will take a long time before everyone is adding exclusively AVIF-encoded rather than JPEG-encoded images to their archives.

maria2 4y ago
Does re-encoding JPEGs as JPEG XL really unlock anything new? The answer is likely no. So this case is not useful to optimize for. As for people's photo albums. The iPhone is already storing new images in HEIF, so JPEGs are becoming less relevant with each passing day. And of course, you can still view the old images perfectly fine as JPEGs.
- mort96 4y ago
  I don't know what you mean by "unlocking anything new". You have identical images at a smaller size. Old images in your photo library aren't becoming less relevant with each passing day. I don't know why you would suggest that they are. I know that iPhone has switched to storing images as HEIF and nothing in my comment suggested otherwise.
  - maria2 4y ago
    > I don't know what you mean by "unlocking anything new". You have identical images at a smaller size. Yes exactly, nothing new is unlocked. So why would I use this format? Was the old size of the images preventing me from enjoying them in any way? No. Of all the old JPEGs out there that absolutely must be losslessly transcoded from the already lossy JPEG encoding, how many are prohibitively large? You can still look at both a JPEG and JPEG XL image locally. Most likely you'd be able to serve both images over HTTP, although the JPEG image may take a bit longer to load. And how many cases require the new and old images be exactly the same? My point is that, if the main selling point of your codec is that you can create the same thing as 30 years ago only smaller, then it's going to be a hard sell compared to other formats out there. If the choice was between JPEG and JPEG XL, then sure, let's use JPEG XL. But the choice is between JPEG XL and other formats with better features. Other image formats like AVIF add new features that enhance images. Yes, the images are smaller, but also way more powerful. Image sequences, for instance, enable new features like "live images." Converting your old JPEG to a smaller JPEG isn't going to magically enable live images. tldr: I'm looking for a reason to care that I can losslessly re-transcode my old JPEGs. Ok, the re-transcoded images are smaller and exactly the same as before, but what is a real world reason why I would need that vs. using the old JPEG directly or re-transcoding it to AVIF?
    - mort96 4y ago
      > So why would I use this format? Because the size is smaller and the quality is the same? Literally the same reason why you'd use any new image format, except that this benefit also applies to existing images, not just new ones? I'm not against AVIF or anything, if you want to add future images which are using fancy animation features from AVIF then that's cool. You don't have to choose between image formats, you can (and already do!) use the right one for the task. > tldr: I'm looking for a reason to care that I can losslessly re-transcode my old JPEGs. Ok, the re-transcoded images are smaller and exactly the same as before, but what is a real world reason why I would need that vs. using the old JPEG directly or re-transcoding it to AVIF? You can use the old JPEG directly, but then your library takes up more space. If you re-transcode your old JPEGs to AVIF, you're losing quality or at the very least irreversibly changing the images. I'm not arguing that it's the world's biggest deal or anything, but a free 20% size reduction on all photos in an image library and all JPEGs sent over the web doesn't seem like a bad deal.

lifthrasiir 4y ago

Individual features of JPEG XL might be not enough, but JPEG XL is a package for all those features, which make it much more attractive than alternatives. And JPEG is really popular while WebP, which finally reached a point of universal support recently, still struggles [1]; it will remain popular enough for at least a decade and probably more. [1] https://w3techs.com/technologies/overview/image_format https://w3techs.com/technologies/overview/image_format