Exhibita

The change a visitor will notice is how a large photograph arrives. A JPEG XL picture can appear whole almost at once, soft at first, and then sharpen as the rest of the file comes in, instead of leaving an empty frame or filling in from the top down. For a full-screen photograph at the top of a page, the first impression is the picture itself, not a gap waiting for it.

Photographs already saved as JPEGs can be repacked as JPEG XL with nothing lost. Apple’s WebKit team, which builds Safari, puts the saving at about a fifth of the file size on average. An archive of images gets lighter without a single pixel changing.

Chrome’s engineers suggest trying it alongside AVIF, the other modern picture format, and expect JPEG XL to be “most helpful for high-fidelity or lossless compression, especially of photographic images.” Firefox can show the format only in its Nightly test version for now, so a site offers the JPEG XL picture with an ordinary JPEG behind it, and each browser takes the one it can show. Nobody sees a broken image.