Page Geometry wrong after watermark

[suntong]

As explained in #201, exif autorot is applied at the start, but such meta data is missing after applying watermark.

Before image: https://fars.ee/v4So

After image: https://fars.ee/dm7d

As we can see that the exif autorot is applied first, but the final exif:Orientation picture orientation is wrong.

UPDATE:

So I took a closer look with identify -verbose after installing imagemagick. Here are the changes in the meta field:

https://www.diffchecker.com/PXo6uJ4r/

I.e., it turns out the Orientation: RightTop was kept as-is in the meta field, but the (Page) Geometry: of 1920x1080 has been wrongly changed to 1080x1920.