CHDK DNG do contain a color matrix, but the quality varies between ports and there no simple, documented process to make a good calibration (dng4ps2 can be used for this, but in practice it is difficult or impossible to get it to work on current cameras). If you come up with a better calibration, we can include it in the source.
Finally got around to looking at this again as I was cleaning up the ixus300 code. Which got me to the CAM_COLORMATRIX1 values - the color calibration part of a DNG image. And that got me to wondering just where those values come? My tentative conclusion is that in many cases, they may just be a C&P from another port.
If so, I probably need to validate (or replace) the ones in the cameras I've ported before posting to pixls.us.
edit : Found this New project: camera color profile calculation : "Gamma value and monitor calibration no matter because the program calculates color matrix by comparing RAW and Jpeg image, it doesn't use only RAW" Interesting! But then I also found this :Quote from: reyalp on 27 / June / 2015, 16:43:51CHDK DNG do contain a color matrix, but the quality varies between ports and there no simple, documented process to make a good calibration (dng4ps2 can be used for this, but in practice it is difficult or impossible to get it to work on current cameras). If you come up with a better calibration, we can include it in the source.
The elph130 and sx160 both have C&P, and they seem fairly OK (meaning "neutral" settings in raw therapee have reasonable colors).
Getting back to the original subject matter of this thread, I guess the pixls.us project mostly cares about the row/column values needed to interpret different RAW files - DNG is easier due to that data being in the header. Inaccurate color calibration probably does not matter to the project?
It does says "if you can provide a more useful photo from a camera model we already support (e.g. a photo of a color target)..."
Quote from: reyalp on 13 / July / 2017, 22:57:07It does says "if you can provide a more useful photo from a camera model we already support (e.g. a photo of a color target)..."I noticed that - and do not remember that from when I originally looked at it. Do you interpret that to mean a color target photo of something like the ColorChecker Classic Card (or maybe a shot of it from a calibrated monitor) instead of a "normal landscape mode" photo - or in addition to?
http://www.ludd.ltu.se/~torger/photography/camera-profiling.html
Recommended shooting a good quality colour checker card, not sure you would get good results from an LCD no matter how well calibrated. You can't daylight and tungsten illuminate an LCD since it's already a light source.
Do you interpret that to mean a color target photo of something like the ColorChecker Classic Card (or maybe a shot of it from a calibrated monitor) instead of a "normal landscape mode" photo - or in addition to?
Unless we can extract something convertible to a DNG color matrix from the firmware...
IMO, the best general solution for CHDK calibration would be a DNG4PS2 style "match the jpeg" system.
