2008.02.15 17:51 "RE: [Tiff] bug? JPEGQUALITY seems not to be read correctly", by Bob Friesenhahn
It is difficult to recreate the q-setting that was used to create a q-table.
Both GraphicsMagick and ImageMagick contain code which does a fine job of estimating the libjpeg equivalent parameters used when writing the JPEG. Perhaps this code can be hoisted?
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/