Adding arbitrary data to an image without affecting usability

Question

I want to include certain information about an image in the image itself. The requirement, i think, is different from the meta data (which i think talks about specific information such as author, date taken etc). The information i want to include may be some random bytes. The image should be still viewable in any standard image viewer. I dont want to "hide" the bytes (m not looking for steganography). I merely want that i can access these bytes from my own application (say Java based) and use / modify the same.

Answer 1

Both EXIF and XMP allow you to add arbitrary tags with whatever data you want. You may want to encode your binary data into ASCII, but that's trivial.

Answer 2

Well, I do not know if it is the better solution, but you can use steganography. It let you store any kind of information (simply bytes) in the pixel data.

An example here, using an image processing framework: http://marvinproject.sourceforge.net/en/plugins/steganography.html