why i still see jpeg in 2020 ?
Internally, JPEG has the key techniques required to compress photos well, and nothing else. Most newer formats are based on the same principles, except each bit is upgraded to the point of diminishing returns.
HEIF and AVIF compress twice as well as JPEG, but in terms of complexity and computational requirements are hundreds of times more complex.
The economics of the camera market right now will make adoption of new formats (and the additional/more expensive hardware in the camera to support it) slow and jpeg is a very reasonable format for photographers to shoot when they don't want/need to shoot raw.
Also, some of the alternative formats have licensing or patent issues that would effectively block wide adoption.
BPG isn't supported by any browsers.
WEBP isn't supported by IE11 or Safari.
Though there are other lossful encoding schemes developed since that either produce better results with the same data size or comparable results with better compression (or both). But the improvements have not been large enough to make the industry as a whole consider making the effort to support these other formats (and in some cases there would be licensing/patent issues making support legally/financially onerous on top of the coding/testing required).
It's not a good idea to enable too many file formats in a browser because of the new security issues, so it really needs to be a huge improvement. I also think WebP was a mistake for this reason, it's not good enough.
From "JPEG 2000: The Better Alternative to JPEG That Never Made it Big": https://petapixel.com/2015/09/12/jpeg-2000-the-better-altern...
JPEG 2000 is a much better image solution than the original JPEG file format. Using a sophisticated encoding method, JPEG 2000 files can compress files with less loss of, what we might consider, visual performance. In addition, the file format is less likely to be affected by ‘bit errors’ and other file system errors due to its more efficient coding structure.
Those who choose to save their files in the JPEG 2000 standard can also choose between utilizing compression or saving the file as lossless to retain original detail. A higher dynamic range is also supported by the format with no limit of an image’s bit depth. Together, these abilities created a much better alternative than the original JPEG solution.
This is confusing. I think they mean that a file is less likely to be corrupt if it's smaller, which is debatable. But I wouldn't use a newer codec just to make smaller files, I'd make them higher quality at the same size. In that case you need redundancy, which is the opposite of compression efficiency.
> A higher dynamic range is also supported by the format with no limit of an image’s bit depth.
JPEG supports this, but most decoders don't because pixel depth is not something you can just abstract away. Do JPEG2K decoders actually support 10/12-bit? HEIF does.
BTW compression efficiency is orthogonal not opposite of structured redundancy that you would want. As a thought experiment, imagine as a last step of coding, encrypting the data with a publicly known key. Theoretical redundancy remains the same, but good luck¹ getting your data back, if you get a bit error.
¹ Imagine a variable length single block cypher was used, multi round CBC or something.