I have removed the option "Force baseline JPEG" from the advanced options in the JPEG save dialog. This option was not very useful and was not well understood by most users. From now on, it will always default to TRUE, meaning that GIMP will only generate baseline JPEG files. In order to avoid breaking backwards compatibility with third-party scripts and plug-ins, the PDB API for file_jpeg_save() is still the same as before, so you can play with the baseline parameter from a script if you really think that you need to set it to FALSE (but this is very unlikely).

So what did that option do? The IJG JPEG library used by GIMP can generate non-baseline quantization tables if that option is set to FALSE. This adds a few extra bits of precision to the quantization tables that have large divisors (large divisors = low quality) in order to preserve a bit more information and generate slightly larger files at very low quality levels. But this also reduces compatibility because some JPEG decoders are unable to read files with non-baseline tables. It is safer to always set this option to TRUE and only generate JPEG files with baseline quantization tables.

Most users do not know that the baseline and non-baseline quantization tables are identical except for quality levels below 23. And the differences between them only start being visible in the image if the quality level is lower than 15 or so. So this option is useless except at very low quality levels, which is something that most GIMP users never use. Instead of using non-baseline tables for very low quality levels, it is better to increase the quality level by two or three points, which will give almost the same result (slightly better quality, slightly larger files).

So that option is now gone from the JPEG save dialog. Of course you can still ask to get it back, but then you'd better come up with very good reasons...

-Raphaël