It's not that simple. Some years ago I used an analog TV card tuned to an empty channel that was giving seemingly white noise and captured frames to generate e

It's not that simple. Some years ago I used an analog TV card tuned to an empty channel that was giving seemingly white noise and captured frames to generate entropy. I only used the least significant bit of each RGB value of each pixel. When I supplied the bits to the diehard testsuite, it complained about a number of patterns and failing tests. The hash function will of course save you, but it's hard to tell the amount of real randomness that's coming from the sensor. update: Oh, I may have misunderstood. If the whole images changes in random ways and is secret, then of course this is fine.