Say you write me a cheque for $50 and I photoshop that into $500, how can they detect that?
I did not touch the serial number and, as the summary suggests, the photo was taken with a lousy cell-phone camera.
If they have a minimal requirement for picture quality, the system will most likely reject a lot of deposit attempts (motion-blur, out of focus, low resolution, etc..)
Doesn't really seem worth the trouble.
If in any problem you find yourself doing an immense amount of work, the answer can be obtained by simple inspection.