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Have they explained their reasons for not backing JPEG-XR instead? This seems to be a step back from JPEG-XR: - No alpha support - Not lossless support (Usefu

by jomohke 16y ago

Have they explained their reasons for not backing JPEG-XR instead? This seems to be a step back from JPEG-XR: - No alpha support - Not lossless support (Useful for the alpha channel, and could encourage more cameras to support lossless images) - No HDR support JPEG-XR also allows different regions of the image to be encoded independently. See wikipedia for more features: http://en.wikipedia.org/wiki/JPEG_XR http://en.wikipedia.org/wiki/JPEG_XR I have no idea what the patent landscape for JPEG-XR is, but I'd be disappointed if we replaced JPEG and didn't get some of these features. The lack of alpha support in JPEG is especially a pain for web developers. PNG does not do photos well.

Groxx 16y ago
Gah! No alpha? Count me out. The web NEEDS alpha channels. I can't count the number of hacks I've seen to get around the lack of an alpha channel in preferred-format-X.
roel_v 16y ago
I've seen the 'no alpha' repeated a few times, but can you give your use cases for alpha in jpeg? I understand the need for alpha channels in gif/png, and have fought the lack of alpha support for years, but for jpg's I don't remember ever needing it, nor can I easily imagine a situation where it would be needed. So I'm interested to learn about where you'd use transparency in jpgs.
- ithkuil 16y ago
  why not? I mean, why should I be forced to use a lossyless image format just because I want it to blend with the background (if the image compresses better with jpeg and the image quality is fine) Are there technical reasons to not implement an alpha in jpeg-like compressions?
  - roel_v 16y ago
    Features shouldn't be there 'just because it's possible', at least not if they may impact other features(1). If greater compression can be reached by leaving out the alpha, and if there's no compelling reason to put it in, it should be left out. 'why not' is not a reason, there needs to be a business case for each feature, in everything. In my experience, and this seems to be a widely held position, the main use case for jpgs is in pictures, as in photographs. The main use case for png (gif) is for graphical elements: borders, menus, etc. Those last ones you want to compress with a lossless format anyway - you need to be sure that a flat menu background is not dithered or doesn't have other artifacts. I understand the question mostly as 'do you need transparency in photographs' and 'do you need non-rectangular photographs where the non-rectangular nature is encoded in the photograph itself, and not part of another rendering in stage in the presentation layer'. Thinking about it more, maybe things like drop shadows or other fancy borders could be case where you need transparency in photos. Otherwise you have to work around it by having the picture as jpg and the border as a separate (or several separate) png's. More requests, harder layouting, etc. I'm not convinced yet that this use case alone is a compelling argument. As for technical reasons to not implement it, I don't know - I'm assuming there are because I'm quite sure that someone at Google must've thought about it and decided against it, they must have had their reasons. (1) I'm reasoning from the assumption that including transparency has adverse effects on file size and/or decompression complexity. Maybe there aren't in which case balancing features becomes a different matter and most of my argument is moot.
varjag 16y ago
Lossless never took off in any variation of JPEG (it was there since the original ITU spec). People don't need it.
- wmf 16y ago
  Compressed raw images would be nice; raw files are huge.

by jomohke 16y ago

Groxx 16y ago

Gah! No alpha? Count me out. The web NEEDS alpha channels. I can't count the number of hacks I've seen to get around the lack of an alpha channel in preferred-format-X.

roel_v 16y ago

I've seen the 'no alpha' repeated a few times, but can you give your use cases for alpha in jpeg? I understand the need for alpha channels in gif/png, and have fought the lack of alpha support for years, but for jpg's I don't remember ever needing it, nor can I easily imagine a situation where it would be needed. So I'm interested to learn about where you'd use transparency in jpgs.

ithkuil 16y ago
why not? I mean, why should I be forced to use a lossyless image format just because I want it to blend with the background (if the image compresses better with jpeg and the image quality is fine) Are there technical reasons to not implement an alpha in jpeg-like compressions?
- roel_v 16y ago
  Features shouldn't be there 'just because it's possible', at least not if they may impact other features(1). If greater compression can be reached by leaving out the alpha, and if there's no compelling reason to put it in, it should be left out. 'why not' is not a reason, there needs to be a business case for each feature, in everything. In my experience, and this seems to be a widely held position, the main use case for jpgs is in pictures, as in photographs. The main use case for png (gif) is for graphical elements: borders, menus, etc. Those last ones you want to compress with a lossless format anyway - you need to be sure that a flat menu background is not dithered or doesn't have other artifacts. I understand the question mostly as 'do you need transparency in photographs' and 'do you need non-rectangular photographs where the non-rectangular nature is encoded in the photograph itself, and not part of another rendering in stage in the presentation layer'. Thinking about it more, maybe things like drop shadows or other fancy borders could be case where you need transparency in photos. Otherwise you have to work around it by having the picture as jpg and the border as a separate (or several separate) png's. More requests, harder layouting, etc. I'm not convinced yet that this use case alone is a compelling argument. As for technical reasons to not implement it, I don't know - I'm assuming there are because I'm quite sure that someone at Google must've thought about it and decided against it, they must have had their reasons. (1) I'm reasoning from the assumption that including transparency has adverse effects on file size and/or decompression complexity. Maybe there aren't in which case balancing features becomes a different matter and most of my argument is moot.

varjag 16y ago

Lossless never took off in any variation of JPEG (it was there since the original ITU spec). People don't need it.

wmf 16y ago
Compressed raw images would be nice; raw files are huge.