Some time ago I developed a module (FieldtypeImageExtra) which extends Fieldtype Image with the ability to add custom fields to an image. This worked well but it had a somehow restricted applicability and did not meet all of our needs. There of course are other useful image modules like CroppableImage or ImageFocusArea, but up to now there was no possibility to combine image cropping with custom fields support. So you had to decide whether to add image cropping or the possibility to add custom f