https://bugs.kde.org/show_bug.cgi?id=418645
--- Comment #14 from caulier.gil...@gmail.com --- MArtin, >Where does this leave us? So various apps "have issues" with raw files. >Including Darktable that clearly suggests to use >DNG files. They do mention >the purple cast here: > >https://www.darktable.org/2012/10/whats-involved-with-adding-support-for-new-cameras/ > >I am unsure which raw lib they actually use at this time in the above link it >reads "darktable doesn’t use dcraw/libraw >and more." yes, darktable has own implementation of Raw demosaicing >Rawtherapee has no issues whatsoever with my DNG files (about 2700). They >claim to use dcraw as raw reader. They even >more suggest going to DNG via >Adobe DNG converter >(https://rawpedia.rawtherapee.com/How_to_convert_raw_formats_to_DNG) In this case we need to use a the closed source RAW to DNG converter. Not he best way... And RawTherapee use also a dedicated Raw engine. >As an aside Ubuntu 18.04 has LibRaw 0.19.5 in the repository. As digikam >appimage has all built in, that is irrelevant. >Manually upgrading to current >exiv2 0.27.2, brings no change in reading the metadata. No, digiKam appImage 7.0.0-beta3 use the lasted libraw version (beta not yet released). You must test with this version which is the current development stage. https://www.libraw.org/news/libraw-snapshot-201910 >I had a look with exiftool the output for an original S3Pro raw file and the >converted DNG. Looking with diff, they are >hugely different. 2 file format different, so 2 ouput differents. It's normal >Could it be an issue of the raw handler that is used? What is the big >difference between Rawtherapee and digikam in >this sense? Thinking into a >different direction: could it be that Rawtherapee demosaics the file before >displaying it? There are 3 possible bugs : 1/ In libraw. After all the Raw mosaic extraction is done with this lib. For the DNG converter, there is no demosaicing stage. The RAw matrix is taken as well as a bytearray and passed to the Adobe SDK for encoding. Note : libraw is also used to extract the color matrix of the RAW data, which is different than all format. I remember that lead libraw author report me that this matrix was deducted by reverse engineering using... Adobe DNG converter (:=))). It's and old talk by mail, and it's difficult to get the right words to explain. So perhaps the colors matrix need to be updated in libraw, simply... 2/ The DNG converter code as well. The way to play with Adobe SDK API is complex and of course code can be bugous. If you is curious code is in gitlab : https://invent.kde.org/kde/digikam/-/blob/master/core/libs/dngwriter/dngwriter_convert.cpp ... and search 'fuji" string to see all specificity to handle colors matrix and rotation of raw data. 3/ The Adobe DNG sdk is too old. Code was not updated since 2012, and Adobe has released 2 new versions since this date. I created few weeks ago a new devel branch in git and updated the DNG sdk to last version, applied fix to compile and tried to use : it crash quickly. So investiguations are required.... Gilles Caulier -- You are receiving this mail because: You are watching all bug changes.
