Analogy to a dictionary attack

It is well known that the one-way encryption scheme is easily broken when the user picks a dictionary word as their password. All an attacker would have to then do is encipher the entire English dictionary and compare the ciphertext of each word to the ciphertext stored in /etc/passwd and pick up the correct word as the password. As such, users are commonly advised to pick more complex passwords that are not words. The dictionary attack can be illustrated like this:

The similarly to the dictionary attack on the blurred image attack lies in the fact that blurring an image is a one-way encryption scheme. You are converting the image you have into another image designed to be unreadable. However, since account numbers only typically go up to the millions, we can assemble a "dictionary" of possible account numbers - that is, all the numbers from 0000001 to 9999999, for example, use an automated image processor to photoshop each of those numbers onto a photo of a blank check, and blur each image. At that point, one can simply compare the blurred pixels to see what most closely matches the original blurred photo we have.

The solution is simple: Don't blur your images! Instead, just color over them :-)