Write crop metadata instead of performing crop
It would be helpful to store the selected crop into metadata of an exported image instead of actually performing the crop, so that in later processing (e.g. making a photo book in scribus) there is the possibility to (slightly) adjust the crop by adding or removing parts of the picture, e.g. to fit a template's aspect ratio or to draw less important picture parts into the bleed.
The question where to store this metadata is not easy to answer. According to http://photo.stackexchange.com/questions/43893/how-to-store-tilt-rotation-and-crop-information-in-metadata, EXIF and IPTC have no fields for that information but xmp metadata fields could be used. Adobe camera raw seems to use
CropRight within the
crs namespace which may or may not be understood by other software. Nevertheless, it may come closest to an industry standard. Some discussion with other projects (inkscape, scribus, gimp) on if and how to use that metadata may be needed. I will ask there.
According to a discussion on the dt user mailing list (starting 2015-11-18), the functionality to store crop metadata instead of cropping can be achieved from lua when access to module parameters is possible, a current work in progress. Especially the handling of modules that rely on 'post-crop' coordinates has to be thought about, e.g. vignette, watermark and border.
#2 Updated by Björn Pettersson over 4 years ago
Christian Mandel wrote:
It would be helpful to store the selected crop into metadata of an exported image instead of actually performing the crop
While I understand the value of this feature I hope that the implementation is very clear on the exported image containing more information than what's seen by default by photo viewers. I would not like things I choose to remove from certain photos to appear later.