Use "Parallax Your Image" to make wallpapers that are optimized for new parallax effect on iOS 7. Also, for greater precision, you can rotate and rescale your image. As a bonus, we decided to add some filters. If you think that something is missing, feel free to leave a comment with your idea. Best ideas from you will be added in one of our next updates.
Note: This app does not make parallax effect, it only adjusts the image to parallax effect requirements.