| 摘要 |
PURPOSE:To precisely detect a focus at high accuracy by providing a correlative pretreatment means for performing either pretreatment for correcting the frequency band of an output signal from an image sensor or pretreatment for emphasizing contrast. CONSTITUTION:The output from the image sensor 10 where the image of an object is formed by an optical system is processed in terms of correlative pretreatment by means of the pretreatment circuit 11 for emphasizing the contrast and the pretreatment circuit 12 for correcting the band and then it is inputted in a correlative operation circuit 13 so that correlative processing is performed to it. Now, band correction processing is performed so that the peak of a correlative signal is sharpened by emphasizing the high frequency side of the frequency spectrum of an electrical signal corresponding to the image of the object, which is usually lowered, and making said frequency spectrum approach to a flat one. In emphasizing the contrast, the amplitude of the AC component of the signal corresponding to the image of the object is enlarged by decreasing the DC component of the signal so that said signal becomes a signal suitable for a correlative operation. Thus, the correlative signal whose peak is sharp is obtained and focus detection can be performed at high accuracy. |
