class.upload.php is a powerful and mature PHP class to manage uploaded files, and manipulate images in many ways. The script is available under a GPL license.
Yes, you loose quality if you process the same image several times.
If you use the class to receive the image, and then post-process it to rotate it, you can try to increase the class image quality to loose a little as possible. Set the jpeg_quality setting to 100, and the image that you will post-process will be of better quality to start with.
Besides, the class already has some rotation methods, which you can use. However, it can only rotate by increment of 45 degrees. It is planned in a next version to implement rotations of any degrees.Reply
If you use the class to receive the image, and then post-process it to rotate it, you can try to increase the class image quality to loose a little as possible. Set the jpeg_quality setting to 100, and the image that you will post-process will be of better quality to start with.
Besides, the class already has some rotation methods, which you can use. However, it can only rotate by increment of 45 degrees. It is planned in a next version to implement rotations of any degrees.