XYB JPEG: Perceptual Color Encoding Tested

https://giannirosato.com/blog/post/jpegli-xyb/

by computerbuster • 3 years ago

49 44 3 years ago

giannirosato.com

computerbuster2• 3 years ago

How does the new cjpegli encoder using the XYB color space stack up compared to the competition?

brucethemoose22• 3 years ago

That is crazy indeed.

I can't remember, do the other encoders automatically change the chroma subsampling? XYB JPEG peaks pretty hard at specific bpp ranges depending on the subsampling.

Also, things like this make me wonder what other tasks would be better in XYB colorspace. BM3D, for instance, performs best in "opponent" color space: https://github.com/HomeOfVapourSynthEvolution/VapourSynth-BM...

computerbuster2• 3 years ago

mozjpeg automatically handles chroma subsampling, scaling up from 4:2:0 to 4:2:2 & then 4:4:4. WebP is 4:2:0 only, AVIF is 4:4:4 only (as tested) & I believe JXL doesn't subsample at all.

yboris4• 3 years ago

In the article they mention JPEG XL (aka .jxl) format that I hope everyone knows about:

https://jpegxl.info/

It is supported by Adobe, included in Safari 17, is behind a flag in Firefox, and was behind a flag in Chrome too until they idiotically chose to remove it despite severe pushback from the community. My take is that it will be one of the most-popular image formats in the coming decade.

bryanrasmussen• 3 years ago

given Chrome's stranglehold how do you see it becoming one of the most popular image formats in the coming decade.

agos• 3 years ago

h.264 did pretty well even if Chrome decided not to support it

zokier2• 3 years ago

Decisions lightly made can be lightly reversed. It's not exactly hell freezes over situation to see jxl reintroduced to Chrome

yboris4• 3 years ago

Their decision is schizophrenic: the JPEG XL format is a combination of two technologies: PIK (developed by Google) and FLIF (developed by Cloudinary) - one of them developed by Google. It is entirely sensible for them to reverse their decision, which came before Safari announced the format would be supported.

Adobe is already supporting the format, and many image editors / browsers are including it.

Finally, adding a WASM polyfil to your website would still yield many benefits, enough to outweigh not-100%-yet-support-by-browsers.

yboris4• 3 years ago

From the same author: https://giannirosato.com/blog/post/image-comparison/

"Considering JXL has been endorsed by Facebook, Adobe, Intel and the Video Electronics Standards Association, The Guardian, Flickr and SmugMug, Shopify, the Krita Foundation, Serif Ltd, Gaia Sky, and many more, the market is most certainly interested. My current optimistic hope is that JXL takes off outside the web among professionals working with tools like the Adobe suite or alternatives, and camera manufacturers, smartphone OEMS, and others take notice & begin to think about JXL more seriously. The benefits cannot be ignored, and it is (in my opinion) the only image format that is in every way superior to JPEG & offers a concrete future for the many existing JPEGs on the Web & beyond."

8n4vidtmkvmk• 3 years ago

I hope I can start saving game screenshots in JXL soon. Pretty sure the HDR is lost when saving as jpeg.

zokier2• 3 years ago

Pretty sure the HDR is lost when saving as jpeg.

Nvidia can capture HDR screenshots in JXR format in supported games.

llm_nerd• 3 years ago

The clear winner here is JPEG XL, which is fully supported in iOS 17 and will have a billion+ capable clients by end of year.

JPEG XL has HDR, is the best codec for photographic type content in all but extremely low file size, is the best codec for cartoon/chart style graphics, has a container that is enormously flexible (want to store a channel for depth or for object detection? You can do it).

yboris4• 3 years ago

Confirming that JPEG XL is a winner. Here's one of the main developers of the format, Jon Sneyers, writing 3 days ago:

JPEG XL: How It Started, How It’s Going

https://cloudinary.com/blog/jpeg-xl-how-it-started-how-its-g...

cubefox6• 3 years ago

While JPEG XL is great in most aspects, in terms of file size AVIF is substantially smaller at medium image quality. AVIF has a lot of problems though, e.g. no progressive image loading or limited resolution. The situation is really frustrating, since there is only a once-in-multiple-decades chance to replace JPEG and PNG, and this chance should better be met with a format that is great at everything. Because if it succeeds, we will be stuck with its shortcomings for a long time, just as we were stuck with JPEG for decades.

srgpqt• 3 years ago

a format that is great at everything

I too want a magical flying unicorn, and maybe we can make one in the next 40 years, but in the mean time I will happily accept to be stuck with a magical jpegxl unicorn that can’t fly.

LoganDark10• 3 years ago

i think png will never be replaced because you will always be able to tell that a png file is lossless, but jpeg is almost always used as a lossy format, and you will never be able to tell at a glance whether someone cared enough to make it lossless for a particular file

(note: losslessly preserving jpeg artifacts is still lossless if those artifacts were already present in the source material)

altairprime• 3 years ago

The clear decade-plus-of-backwards-compatibility-in-globally-deployed-software winner is XYB JPEG, a category in which neither XL not AVIF are valid comparisons at all.

This in no way contradicts your points about the forward opportunities of XL. For anyone that seeks the best backwards-compatibility for display use, there’s now XYB as well.

LoganDark10• 3 years ago

wonder if there is a perceptual color system that accounts for the rare fourth color receptor...

https://en.wikipedia.org/wiki/Tetrachromacy#Tetrachromacy_in...

don't know if that would be reproducible on a regular RGB display, though

orbital-decay• 3 years ago

There isn't even a way to account for individual differences, let alone for things like tetrachromacy. Color blindness is probably easier (at least crudely), but AFAIK it also varies between the same types. So unless you profile your perception individually, we're stuck with the biggest cluster of the "average human vision system".

wpietri• 3 years ago

Reading how tuned this is for the quirks of human perception, it makes me wonder how difficult alien technology would be for us to comprehend.

LoganDark10• 3 years ago

i see different colors per eye so yeah

cubefox6• 3 years ago

don't know if that would be reproducible on a regular RGB display, though

It wouldn't, and also not with standard camera sensors. The RGB subpixels correspond to the main wave length sensitivity of the three color cells in the eye. I think for tetrachromy there is a fourth cell for UV light with shorter wavelength than blue. There is no way to support this with our current tech stack.

LoganDark10• 3 years ago

this reminds me of how designing for "the average human" leaves out anyone with even slightly superhuman capabilities, and how frustrating this is for us when our capabilities surpass what designers thought were good enough. for us, this happens frequently with monitor PPI and HMD PPD, but i can imagine someone with tetrachromy theoretically being able to perceive colors that computers can't reproduce, and wondering why computers lack these colors, only to find that this is supposedly an impossibility that was optimized out

as an example, apple's new HMD advertises things that simply can't possibly be true, so we probably won't be getting one any time soon. there's zero reason to upgrade from a simple hp reverb g2 when the only difference between two blurry headsets is that one of them costs four times more. we'd rather be conscious of this than try to fix it when no solution currently exists

this isn't saying displays for tetrachromy should have been the norm, as that's very wasteful on most people. but maybe displays for tetrachromy could have existed, somewhere, in some market, just like tech devices with placebo-level specs tend to exist in some market

blincoln• 3 years ago

TLDR: A display for people or other creatures with true tetrachromatic vision (not just an additional receptor, but the ability to perceive it as a distinct primary colour) would need to be able to output that fourth primary colour, but there doesn't seem to be enough data to determine conclusively at this time if women with a fourth type of cone perceive a fourth primary colour.

The one study I've been able to read the full text for that involved determining spectral sensitivity of a woman with distinctly tetrachromatic vision[1] indicates that she had some cones with a peak in-between what most people would see as red and green,[2] and could consistently and accurately discriminate between colours that would appear identical to most people.[3] Unfortunately (and surprisingly, IMO), it doesn't discuss her subjective perception, i.e. does she perceive a true fourth primary colour?

It seems like a very, very rare gift, so IMO it's hard to even determine if the women who have it respond in similar ways, which would be a prerequisite for developing a display for them. Everyone else the authors tested who had a fourth type of cone couldn't actually discriminate between colours beyond someone with the typical three types. It would be interesting to see if they gained the discrimination ability by wearing glasses with extremely narrow bandpass filters for their cones' center wavelengths, like the ones that give men with red/green colourblindness the ability to distinguish between red and green.

[1] https://jov.arvojournals.org/article.aspx?articleid=2191517 - which cites a much earlier paper by two of the same authors (https://pubmed.ncbi.nlm.nih.gov/8351822/) that also included the subject "cDa29". [2] Search for "Simulated cone fundamentals for cDa29" in the first paper linked in [1] [3] "one participant cDa29 [...] behaves as if she has access to an additional cone signal: she made no errors at any value of (R670 / (R670 + G546)) [...] and her response times not only are faster than those of other participants [...] but are roughly even across the stimulus space"

LoganDark10• 3 years ago

thank you <3

tambourine_man• 3 years ago

Images are completely green in Safari 15 and Photoshop. Works fine in Chrome and Firefox

XYB JPEG: Perceptual Color Encoding Tested

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