I've just started using ufraw-batch as a delegate to imagemagick for handling dng files.
But the picture is not cropped as the DNG specifies it.
Here is the interesting part of the XMP data provided by exiftool :
Crop Left Margin : 0
Crop Right Margin : 0
Crop Top Margin : 0
Crop Bottom Margin : 0
Cropped Image Width : 3888
Cropped Image Height : 2592
Default Crop Origin : 10 5
Default Crop Size : 3888 2592
Crop Top : 0
Crop Left : 0.269117
Crop Bottom : 0.846325
Crop Right : 0.833333
Crop Angle : 0
Crop Constrain To Warp : 0
Notice that the picture is 3908x2602.
I could fall back on the "good side" by reducing the pict to 3888x2592 as mentionned, and then apply crop with the crop ratios given.
Is there a way to do it natively ? (ufraw says it has an auto-crop features, but I can't get it to work)
I also have a case where the DNG has lot of XMP data which contain information about several snapshot of the same picture. (e.g.: one for the whole picture, one for a detail, one for the whole picture in black and white, etc).
I don't know how to handle those cases properly.
I can provide test files, but not publicly.