A data structure of an image signal includes a reproduction cycle identifier indicating whether the cycle of image display for each frame is variable or not. In one embodiment, the detecting operation may include sending an interrogation signal from the power control circuitry to the variable output DC power source, and evaluating a response to the interrogation signal to determine the type of said variable output DC power source. The non-volatile storage device may be configured to store at least three bits of data per storage cell. Another aspect of the invention includes using the variance of a set of noise feature vectors andor channel distortion feature vectors when identifying the clean signal feature vectors.