Averaging array for ccd imagers

Abstract

In the present invention, a method is set forth for the generation of an average signal for the pels of a neighborhood, i.e., a matrix array, without corrupting individual pel values. The system which performs the method includes a metering circuit, an output register, and a filtering array. The metering circuit transfers a fixed proportion of charge signals representing a pel row in parallel from the CCD array to the filtering array. The remaining charge signals remain in an output register, which outputs them as representations of the individual pels of the image. One type of filtering operates by averaging over non-overlapping regions within the image. Charge signals which have been transferred by the metering circuit are added together along the vertical axis and are transferred to a vertical average register, whereupon, this value is serially shifted out of the vertical average register and into a horizontal summer. The horizontal summer adds the output charge along the horizontal axis. This results in an average of the individual pel values within a region of the image which is outputted form the device. Another type of filtering operates by averaging overlapping windows within the image. The charge signals from the metering circuit are split into multiple portions, each of which contributes to a different vertical sum for an averaging window. The vertical sum charge signals are split into multiple portions, each of which contributes to the area sum for an averaging window, which is created by horizontal summing performed in parallel. The resulting area averages are outputted.