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Kalpanika / x3f

Tools for manipulating X3F files from Sigma cameras
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Fixing DNGs to work with more raw converters #91

Open borissimo86 opened 7 years ago

borissimo86 commented 7 years ago

Could the following be implemented to make Kalpanika DNGs more compatible with raw converters?

Stated by Brian Griffith (author of Iridient Developer) at https://www.dpreview.com/forums/thread/3912319

"The per channel white levels is likely what caused the most noticeable color issues with the images previously and would probably be an easy change to improve theDNG compatibility with even more RAW processors. Just multiply the color channels prior to saving to DNG so that they share the same identical maximum channel white.

The use of the gain map DNG opcode was the other missing piece in prior versions of Iridient Developer and that too could probably be baked in without much if any negative impact on the final image just shift the maximum white point some such that no clipping occurs after applying the gain maps..."

rolkar commented 7 years ago

Thanx for your information. I assume we care about both white level and gain map. But, Erik would know that better.

erikrk commented 7 years ago

The channels could in principle be multiplied so that the white levels are the same, but it wouldn’t necessarily fix the problem. It depends on if the problem is with the actual handling of per channel white levels, or with handling of white balance. The gain map could in principle be baked in, but then there wouldn’t be any way of correctly specifying the white level. It has to be specified exactly where clipping occurs. If the white level is set too high, clipped data will be handled incorrectly.