JXL is two separate image formats stuck together. An improved version of JPEG that can also losslessly and reversibly recode most existing JPEG images at a smaller size, and the PNG like format (evolved from FLIF/FUIF) that can do lossless or lossy encoding.
“VarDCT” (The improved JPEG) turns out to be good enough that the “Modular” mode (The FLIF/FUIF like one) isn’t needed much outside of lossless encoding. One neat feature of modular mode though is that it progressively encodes the image in different sizes, that is if you decode the stream as you read in bytes you start with a small version of the image and get progressively larger and larger output sizes until you get the original.
Why is that useful? Well you can encode a single high DPI image (e.g. 2x scale), and then clients on 1x scale monitors can just stop decoding the image at a certain point, and get a half sized image out of it. You don’t need separate per-DPI variants.
Oh, it’s right at the top of their site. Brainfart.
My computer supports JXL, read and write. Is JXL lossless?
JXL isn’t lossless by default but you can encode losslessly and still get meager to fair file size reduction compared to WebP or PNG.
JXL is two separate image formats stuck together. An improved version of JPEG that can also losslessly and reversibly recode most existing JPEG images at a smaller size, and the PNG like format (evolved from FLIF/FUIF) that can do lossless or lossy encoding.
“VarDCT” (The improved JPEG) turns out to be good enough that the “Modular” mode (The FLIF/FUIF like one) isn’t needed much outside of lossless encoding. One neat feature of modular mode though is that it progressively encodes the image in different sizes, that is if you decode the stream as you read in bytes you start with a small version of the image and get progressively larger and larger output sizes until you get the original.
Why is that useful? Well you can encode a single high DPI image (e.g. 2x scale), and then clients on 1x scale monitors can just stop decoding the image at a certain point, and get a half sized image out of it. You don’t need separate per-DPI variants.
👍
Came here for the meme, learned something instead.