[atdt]

When using Jpegli as a drop-in replacement for for libjpeg-turbo (i.e., with the same input bit-map and quality setting), will the output produced by Jpegli be smaller, more beautiful, or both? Are the space savings the result of the Jpegli encoder being able to generate comparable or better-looking images at lower quality settings? I'd like to understand whether capitalizing on the space efficiency requires any modification the caller code.

[JyrkiAlakuijala]

The output will be smaller after replacing libjpeg-turbo or mozjpeg with jpegli. You don't need to do any code changes.

[pizza]

I think the main benefit is a better decorrelation transform so the compression is higher at the same quality parameter. So you could choose whether you want better accuracy for the same quality parameter, or lower the quality parameter and get better fidelity than you would have otherwise. Probably to get both most of the time, just use JPEGXL