PURPOSE: To speed up the detection speed for the highest correlation between a pair of video image data groups showing an object video of automatic focusing cameras, etc.

CONSTITUTION: The circuit is provided with a 1st register group 10 equipped with serially connected registers 11-15 accepting each evaluation value of an evaluation function (f) showing the correlation between video image data groups DL and DR by right and left image sensors 3L and 3R of an object 1 and storing them in succession, 2nd register group 20 equipped with registers 21-25 corresponding to the register group 10, connection means 30 connecting the registers corresponding to the register groups 10 and 20, and comparison circuit 40 sending a highest value detection signal DS when the evaluation value in the register 13 at the center of the 1st register group 10 is lower than the evaluation value in the before and after registers 12 and 14. Based on the signal DS, the plural evaluation values in the 1st register group 10 is shifted to the 2nd register group 20. Then the plural evaluation values are outputted for an examination interpolation circuit 7 or the like in a batch.