Hi Stefan,
Thank for your question! Firstly, the latest 1.5 and 1.6 have an AutoDev that behaves differently and more controlled (and come with two more controls too).
Develop, as does most other software, takes a specific mathematical formula, where some terms/variables can be varied. Develop, in StarTools, uses a specific function introduced by Kunihiko Okano that emulates the response of a traditional film camera (
more info on the function here). Other software uses (or offers) ArcSinH as well, however this is mostly because this function is better at color retention (an issue that ST obviously does not suffer from thanks to its signal evolution Tracking).
AutoDev, on the other hand, analyses the image for actual content and detail, and then formulates a custom transformation curve to what is needed to bring out all detail it detected as much as possible. This means that the transformation curves can look very different between images (or Regions of Interest) indeed. AutoDev images - especially as of 1.5/1.6 will show much better controlled highlights and shadows,
providing excellent starting points for further detail recovery or accentuation using more advanced tools.
To illustrate the effectiveness of AutoDev;
http://download.startools.org/Tutori...utodev_SBS.png
(M101 by Jim Misti, left Develop, right AutoDev).
AutoDev autonomously managed to figure out a stretch that is very close to a manual DDP but allocated slightly more dynamic range to the faint, large scale detail (for example 8 o'clock, 11 o'clock); bringing out this detail is now easier (if you spotted it to begin with!).
TL;DR Develop uses one function that fits-them-all, while AutoDev uses custom functions that - objectively - yield more appropriate results for the dataset at hand.