| 摘要 |
PROBLEM TO BE SOLVED: To stably detect a target existing in a flat area with low brightness around the edge of high-brightness clutter by providing a plurality of window circuits for outputting the brightness values of picture elements adjacent to each other. SOLUTION: A first window circuit 11 outputs brightness values of picture elements adjacent to every picture element, and a second window circuit 12 outputs the brightness value of the picture element adjacent to one specified by the circuit 11. A third window circuit 13 outputs the brightness value of the picture element adjacent to one specified by the circuit 12, and average value calculation circuits 14, 15 and 16 output the output values of the circuits 11, 12 and 13 respectively. A window selection circuit 17 selects such a window circuit that outputs the maximum value among the output values of the circuits 14, 15 and 16, and a circuit 18 for calculating typical value of selected window outputs the typical value from the output values of the selected window circuit. Thus, an optimal typical brightness value can be calculated and the target can be also detected stably. |
