To extract the most data out of the image you need to start from a linear profile; but the problem with this is the images look like [admin: avoid swearing please] when you first load them (extremely flat and insipid). Adobe knows that this would create a negative impression (especially for Lightroom) so they don't do it - unfortunately they don't even provide the option for people who want to use linear profiles.
I asked about embedding a linear profile on CHDK IRC last night - mostly because I was looking for a neutral starting point for exploring calibration. But now the possibility of embedding one in the DNG gets interesting based on your comments. If I understand correctly, that would give you the most useful image for extracting data as an input to something like Lightroom, as Lightroom won't let you override the DNG's built-in calibration matrix with a neutral one?
What if we add an option to the CHDK DNG menu for calibration? DNG Calibration [ Normal ] or DNG Calibration [ Flat ]Default to normal so the punters don't get confused but make the other choice an option?
Or is creating a linear profile tricky too?
This is not all that hard; but requires a colour card and extra software
This might be an option worth to add to the DNG settings in CHDK.
Linear profiles are still useful in LR (at least to me); but not so much for CHDK - getting good matrices is key.
Best for keeping the general populace happy; but probably the worst solution photographically.
damonlynchDec '16I've analyzed every file in the raw sample DB. Last I checked those CHDK files are impossible to get metadata out of using mainstream free software tools. Maybe that's not important to you as someone interested primarily in rawspeed? But it is important to myself, and maybe to others too. Personally I find them useful as samples of garbage input that my program should handle gracefully. So I think it would be very useful for the DB to differentiate between categories of RAW.
This might be an option worth to add to the DNG settings in CHDK. Linear profiles are still useful in LR (at least to me); but not so much for CHDK - getting good matrices is key.
Quote from: philmoz on 14 / July / 2017, 20:06:08This might be an option worth to add to the DNG settings in CHDK. Linear profiles are still useful in LR (at least to me); but not so much for CHDK - getting good matrices is key.tl;dr -> most popular RAW processing software will usually ignore the embedded exif Color Matrix calibration data in a DNG image if it can.The embedded calibration matrix is usually ignored if the software has a valid profile for the camera model.
One option might be to try and create a collection of proper colour profiles for cameras without native RAW and host them somewhere.