From the MWG documentation:
Rotation Issues
As discussed earlier in section 5.4, regarding Exif Orientation, if metadata is not updated upon a physical rotation of the image data some applications may incorrectly display the image. Region metadata is applied to the stored image. When applying a rotation by applying Exif Orientation, the rotation must be applied to the regions as well. Otherwise, the regions will not apply to the areas intended. If the stored image is rotated, the region metadata must also be updated to reflect the change.
So the region coordinates should be independent of the EXIF Orientation for the MWG RegionInfo metadata.
If this is different for the Microsoft regions, then we have a problem.
We also have a problem if the image was physically rotated after defining the MWG regions.
- Phil