| 摘要 |
PURPOSE:To evaluate whether the amount of exposure is proper or not with regard to individual parts of a screen, by performing binary coding on the basis of two reference voltages, i.e. value a little lower than the saturation level and value a little higher than a black level of a video signal. CONSTITUTION:A composite video signal is outputted to the binary coding circuit consisting of comparators 28 and 29, a video signal composite circuit 30, and an averaged light metering circuit 14 when reproducing switch 24 is set to ''1'' position. A signal S1 applied to the comparator 28 is converted into a binary-coded signal which has a logical value ''1'' where the level exceeds a white level set value VS set a little lower than the saturation level of the video signal and a logical value ''0'' where the level does not exceed the set value. Similarly, the signal applied to the comparator 29 is converted into a binary-coded signal which has ''1'' where the level is lower than a set value VD set a little higher than the black level of the video signal and ''0'' where the level is higher. Then, gate circuits 31 and 32 OR the binary-coded signals S2 and S3 from which blanking signals are removed to generate and input a binary-coded picture quality defective signal S4 to a video processing circuit 35, thereby obtaining a binary-coded video signal which specifies a picture-quality defective part. |
