Unfortunately, most phashes are trivial to circumvent. Imperceptibly rotating saturation or leveling brightness will result in a new phash. (If you've found a

Unfortunately, most phashes are trivial to circumvent. Imperceptibly rotating saturation or leveling brightness will result in a new phash. (If you've found a robust, patent-unencumbered phash, please share, I'd love to use it for PhotoStructure!)