I read this but it didn't ask the question I want answered. How is Chase Mobile Deposit Secure?
What I want to know is how do they avoid accepting a Photoshopped check?
When someone gives me a printed check(which is the majority of checks I get), I could extremely easily take it, change the value on it (including the text portion) to some arbitrary number, change the date to a couple days before I plan on depositing it, and advance the check number by 20 or so, so that the bank doesn't see it as a check that has already been deposited. As one last precaution in case they check the signature for matching a previous check exactly, I can take the person's signature off and Photoshop in one from another document or really old check.
Once I forge the check on the computer, I could print it out and cut it to the right size. Take the picture, and now what? Does Chase have any way to verify that it is not a real check other than waiting to see if the other customer to says something about it?
(as a side note, if I tried to bring this into a bank, it would be very obvious that it is fake)
It doesn't help in Chase's favor that the app takes such LOW quality pictures either. That problem works in my favor because even somewhat large defects in my Photoshopping will be completely hidden by the low quality picture.
 We should assume the forged check looks just like the real one in the picture taken by the app (because it actually would.)
Just it would be check number 520 instead of 500 so that the bank doesn't see it as a duplicate.