JPS54104329A - Out-of-focus detection method of picture image - Google Patents

Abstract

PURPOSE: To detect out-of-focus of picture image accurately and easily regardless of large or small of the quantity of transmitted light, by comparing the level gradient value at a turning point from positive to negative or from negative to positive of the level gradient of electric signal inputted into a processing part with the threshold value.

CONSTITUTION: While scanning an optical beam on a video medium 3 on which picture image is recorded, the transmited light of the video medium 3 is Fourier transformed by a Fourier transforming lens 4 to obtain a Fourier pattern, which is passed into a high pass filter 5 to enter a photoelectrical transducer 7. From the transmittance distribution function with respect to the picture image, the high frequency component thereof is transformed into an electric signal in time series, and is processed in a processing part 10. In the processing part 10, the level gradient value at turning point from positive to negative or from negative to positive, or the both turning points, of the level gradient of said electric signal is compared with the threshold value, and the out-of-focus of picture image is detected.

COPYRIGHT: (C)1979,JPO&Japio