Digital camera photos are often saved as JPEG with an EXIF "orientation" tag. To display correctly, images need to be rotated/mirrored depending on which orientation is set, but browsers ignore this information rendering the image. Even in large commerical web apps, support for EXIF orientation can be spotty 1. The same source also provides a nice summary of the 8 different orientations a JPEG can have:
Sample images are available at 4.
The question is how to rotate/mirror the image on the client side so that it displays correctly and can be further processed if necessary?