Hi,
in the meantime I got a S100 for test purposes. CHDK writes a dng which lightroom do not recognize as a S100 file. This is great news since lightroom does not apply the built in development rules which remove a lot of pixels and decrease the field of view.
Here is a very quick and dirty result: I opened an image from the Adobe lense creator package and took a picture from my monitor screen. I imported the resulting chdk-dng as well as the built-in s100-raw file to LR. I applied a SX230 lense profile to the dng (since this profile fits best at the moment - I have to create a seperate one for the S100) and the S100 lense profile to the raw file and compared both images.
The dng file has a lot of potential regarding field of view as you can see from the linked image. It is really amazing how much pixel the dng recovers. Nevertheless, the lense profile of the SX230 is not perfect (which I knew before). When I am able to create a dedicated lense profile for the dng the results will be awesome.
https://www.dropbox.com/s/2via9fhrrpykge3/s100-raw-vs-dng.JPG Nevertheless, I do not understand why the dng shows totally other values regarding ISO and exposure although it is the same image. Is it a problem wih the CHDK DNG generation?