There is a lossless ultra-packer for existing JPEG files. It's completely reversible, you can get byte-for-byte identical JPEGs back.
Then there is "VarDCT" mode, which acts like JPEG, lossy Webp, or video codecs.
Then there is "Modular Mode", a completely different kind of codec that has different kinds of compression artifacts than JPEG-like codecs. The compression artifacts you see tend to be more like sections becoming more pixelated, or slight color differences. Strong edges don't have ringing artifacts. Modular mode mainly is used for lossless compression, but also allows lossy compression.
I investigated using JPEG XL for high speed applications but encoding time was much slower than JPEG with libturbojpeg even if you reduce encoder complexity to a minimum
> I investigated using JPEG XL for high speed applications but encoding time was much slower than JPEG with libturbojpeg even if you reduce encoder complexity to a minimum
The article has libjpeg-turbo with an encoding speed of 49 MP/s and JPEG XL at 50 "based on four CPU cores":
it's much much faster than the other alternatives tho. and staying with JPEG isn't really ideal with it's low quality and limited options going forward.
JPEG XL is three different codecs in one.
There is a lossless ultra-packer for existing JPEG files. It's completely reversible, you can get byte-for-byte identical JPEGs back.
Then there is "VarDCT" mode, which acts like JPEG, lossy Webp, or video codecs.
Then there is "Modular Mode", a completely different kind of codec that has different kinds of compression artifacts than JPEG-like codecs. The compression artifacts you see tend to be more like sections becoming more pixelated, or slight color differences. Strong edges don't have ringing artifacts. Modular mode mainly is used for lossless compression, but also allows lossy compression.
I believe JPEG XL is now supported in macOS 15 and iOS18.
edit: previous discussion about it https://news.ycombinator.com/item?id=41598170
I investigated using JPEG XL for high speed applications but encoding time was much slower than JPEG with libturbojpeg even if you reduce encoder complexity to a minimum
> I investigated using JPEG XL for high speed applications but encoding time was much slower than JPEG with libturbojpeg even if you reduce encoder complexity to a minimum
The article has libjpeg-turbo with an encoding speed of 49 MP/s and JPEG XL at 50 "based on four CPU cores":
* https://cloudinary.com/blog/how_jpeg_xl_compares_to_other_im...
it's much much faster than the other alternatives tho. and staying with JPEG isn't really ideal with it's low quality and limited options going forward.
(2020)