@bondsbw: Text parsing would not be trivial. I'm not sure how one can predict a blurring algorithm's output in advance, but that would be the best approach, I agree. Perhaps one could manually create the expected blurred image and rely on the blurring algorithm to exactly re-produce this image. If the blurring algorithm is not predictable then some other pattern recognition would be required. A unit test for all black should not be difficult if that is a problem. I am not familiar with image blurring codebases or if their output is predictable, fwiw.