DIFFERENCE CALCULATION CIRCUIT, PROJECTOR, AND CONTROL METHOD OF DIFFERENCE CALCULATION CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide a difference calculation circuit capable of detecting change in the whole image.

SOLUTION: The difference calculation circuit includes: a plurality of frame memories (a first frame memory 32a and a second frame memory 33a) which store image information based upon an input image signal; a pixel difference calculation unit 33c1 which calculates a difference between the plurality of frame memories as a pixel difference value with respect to pixel information as information by pixels based upon the image information stored in the frame memories; a difference average calculation unit 33c2 which calculates an average of the pixel difference values as a pixel difference average value; an all-pixel calculation unit 33c3 which calculates the pixel difference average values with respect to all the pixels based upon the image information; an all-pixel average calculation unit 33c4 which calculates an average of the pixel difference average values of all the pixels as an all-pixel difference average value; a comparison unit 33c6 which compares the all-pixel difference average value with a predetermined threshold; and a notification unit 33f which outputs a predetermined notification signal based upon a comparison result of the comparison unit 33c6.

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