I wonder if it is possible to write a lightroom plugin, which applies crop rectangles to a set of images?
Of course I do not just want to duplicate the crop, I'd like to set a different crop to every image, based on some computations.
Can this be achieved with lightroom plugins, or would I need to try a different approach?
Unfortunately as of Lightroom SDK 3.0 it is not possible to programmatically crop an image. There is no official reason for this, but it seems to stem from a two linked causes. First, the only way to change an image is to use LrDevelopPreset. This class allows a develop preset to be modified and applied to an image. And second, develop presets cannot store crop settings.
There are a couple of threads in the Lightroom Feature Request forum mentioning the inability of crop settings to be specified in a develop preset. No generally applicable workaround has been found.