ROBUST AUTO-FOCUS ALGORITHM FOR MULTISPECTRAL IMAGE SYSTEMS

摘要

An autofocus metric approach for focusing video images, automatically, based on images taken during a focus sweep in which a focus cell is repositioned for each of the images is provided. The approach includes, given an edge detected image from the focus sweep and an associated focus cell position in the focus sweep, an autofocus engine dividing the edge detected image into sub-images. For each sub-image, the autofocus engine calculates a normalized edge detection strength and compares it to a threshold. Based on the comparison, the autofocus engine determines whether an edge is present in the sub-image. Based on the determinations of edges in the sub-images, the autofocus engine calculates an autofocus metric associated with the given focus cell position. The autofocus engine provides the autofocus metric together with autofocus metrics associated with other focus cell positions to focus the video images.