Auto-focus control using image statistics data with coarse and fine auto-focus scores

Abstract

Techniques are provided for determining an optimal focal position using auto-focus statistics. In one embodiment, such techniques may include generating coarse and fine auto-focus scores for determining an optimal focal length at which to position a lens associated with the image sensor. For instance, the statistics logic may determine a coarse position that indicates an optimal focus area which, in one embodiment, may be determined by searching for the first coarse position in which a coarse auto-focus score decreases with respect to a coarse auto-focus score at a previous position. Using this position as a starting point for fine score searching, the optimal focal position may be determined by searching for a peak in fine auto-focus scores. In another embodiment, auto-focus statistics may also be determined based on each color of the Bayer RGB, such that, even in the presence of chromatic aberrations, relative auto-focus scores for each color may be used to determine the direction of focus.