Fluffy-Jackfruit-930 t1_ixus65r wrote on November 26, 2022 at 3:10 PM

Reply to comment by strangway in ELI5: In recent years, new formats like webp and jfif have started popping up. However, if I rename them to gif or jpeg, they still work. How can it be that renaming the extension doesn't ruin the image format? Why do they even exist then? by Luthemplaer

It's an excellent format in many ways, but had a number of problems.

The technology it used (wavelet transform) was new and dozens of new start up companies were out there patenting everything wavelet related they could think of. Lawyers were concerned that JPEG-2000 was potentially impacted by a ton of patents. As a result, very little software supported it, and that which did was typically highly priced professional software, with JPEG-2000 support as an additional expensive option.

The wavelet transform is substantially more complex than the discrete cosine transform used in JPEG 1. Saving and opening files can be dramatically slower. High resolution files which would take 1 second to display in JPEG 1, could take minutes with JPEG 2000 on a similar year 2000 CPU.

The new features JPEG2000 offered (lossless compression, less visible lossy compression artefacts, HDR, imaging tiling, hyperspectral imaging and 3D) were of limited interest to most users at the time and did not outweigh the cost and CPU requirements, and even today, many of the features are still niche.

Some industries did use JPEG2000, mainly the medical and scientific (e.g. satellite imaging) communities, because of it's advantages and the fact that the had a clear need for the features, could mitigate the disadvantages and were prepared to pay. For example, in medical imaging JPEG2000 was typically used for transfer of images on CD/DVD or over a slow WAN network connection. If it took 10 minutes to compress the images before burning to a CD, and it allowed only 1 disc to be burned instead of 2, that was a big advantage.

The patent issue has been a recurring problem. For example JPEG 1 is generally thought of as being always lossy. There is, in fact, a lossless mode - but at the time JPEG 1 launched, the technology it used (arithmetic coding) was heavily patented, and most companies developing JPEG software stayed far away from the lossless mode. Lossless JPEG 1 is a very niche file format - mainly only used for medical image transfer - with almost no software able to open it.

Intergalacticdespot t1_ixxtf8s wrote on November 27, 2022 at 5:25 AM

Technically whichever company invented jpeg owns all pictures encoded as .jpeg. I'd imagine it wouldn't hold up in court because it's been unenforced for like 20-30 years now. But in theory jpeg itself is the same way. Was one of the earliest mass copyright attempts. And why I still prefer gif or png when at all possible.

Fluffy-Jackfruit-930 t1_ixzf36g wrote on November 27, 2022 at 4:22 PM

JPEG was developed by the Joint Photographic Experts Group and the CCITT, with the intention of being a free and open standard. Where they did use patented technology, they specifically negotiated with the patent holders to get free use rights.

Lossless JPEG, in particular, used a ton of patented technology, whereas lossy JPEG was pretty much patent-free. Some lawyers were concerned that the agreements may be CCITT/JPEG might not cover all patents, so lossless JPEG was immediately hamstrung by legal concerns, plus the fact that for most purposes, lossy JPEG was plenty good enough and gave much better compression.

There was a bit of a controversy, because in 2002, a company with a patent on the DCT technology behind lossy JPEG, suddenly started instructing lawyers to sue any company using JPEG files or using software which could handle JPEG files. This patent wasn't listed in the legal documents produced by JPEG/CCITT, so they didn't have a legal agreement in place. In the end, the company decided to drop the claims, because the patent wasn't actually valid.

GIF has also been problematic from a patent and legal perspective, although PNG has been designed from the ground up to be open and avoid patented technologies completely.