My iPhone does that too.
You don't need to resize the pictures - the Bookcrossing website resizes them automatically. I guess what you really want is for the picture to be in the correct orientation (portrait in this case).
I have a method of fixing it but it is fiddly. I also do it from a computer, not the phone.
1. Go to the book's link. In this case, it'shttp://www.bookcrossing.com/---/14742524/
2. Left click on the picture in the wild release notes. It should pop up as a larger picture.
3. Save that picture to your computer. Use what imaging software you have on your computer to rotate the picture and save it in the correct orientation.
4. Go back to the book's release notes.
5. Click on "upload journal picture".
6. You can choose to remove the current image. Or you can just upload the new image. That should automatically override/replace the old image.
7. It may not look as if the old picture has been replaced right away. There is a current known "bug" that means picture updating seems to be delayed. Bookcrossers have reported delays ranging from several hours to several days. In my own experience, it can be several weeks.
But, when asked to check, other Bookcrossers report being able to see the new image. So it may be some sort of caching issue.
8. If you want to check that the new picture has been uploaded, repeat step 2. The larger image that pops up should be the new picture. If so, rest assured that the smaller picture will update eventually. It will just take a while.