Patent ID: 6545715
Filing Date: 2003-04-08
Classification: H04N

Abstract:
A focus control apparatus using an adaptive filter for determining a focus value used for controlling the focus of a lens, comprising:adaptive low-pass filtering means for applying a mask of a predetermined size to an image signal captured through the lens, said adaptive low-pass filtering means comparing brightness level differences between a central pixel located in the center of the mask and pixels adjacent to the central pixel with a threshold value, multiplying a weight calculated in response to the result of comparing the brightness level differences by a brightness level of a concerned pixel in the mask, adding together the multiplication results of all the pixels, and outputting an addition result as an adaptively low-pass filtered image signal; a high-pass filter for filtering a high-frequency component of the adaptively low-pass filtered image signal; absolute value calculating means for calculating absolute values of the image signal in which the high-frequency component is filtered; and accumulating means for accumulating the absolute values and outputting an accumulated value as the focus value of the captured image signal.