| 摘要 |
PURPOSE:To automatically detect the position of horizon in an image of a TV or infrared camera with a satisfactory S/N ratio by comparing sums of video signals of scan lines in the horizontal direction. CONSTITUTION:When detecting a target, a scanning is done only near the horizon while video signals A are inputted into an addition circuit 1 and added values are memorized temporarily into a register A 2 to sum up video signals for one line. Then, while these signals are held in a register B 3, video signals for one line from the subsequent scanning are inputted into the addition circuit 1. Thereafter, the sum of signals for one line from the subsequent scanning is subtracted from the sum of some preceding video signals with a subtraction circuit 4 and the results are held into a register C 5 during one scanning period. Differential signals between the scan lines held in the register C 5 are compared with a reference set value by a comparator 6 and when they exceed the set value, a horizon detection signal B is outputted as indicating horizon. Thus, the detection of horizon can be done with a satisfactory S/N ratio by comparing sums of horizon video signals on real time in parallel with the signal processing for automatic detection. |
