Patent ID: 7598996

Claim:
A method of focusing a digital camera module with an image sensor, the method comprising: capturing a single image of a predetermined test target at a known location and a background with the digital camera module; defining, prior to the capturing of the single image, a plurality of analysis regions of the single image that are to have focus quality analyzed and remaining regions of the single image that are not to have the focus quality analyzed based on the known location of the predetermined test target; determining the focus quality of the single captured image with the image sensor based on the plurality of analysis regions of the single capture image, each of the analysis regions including a respectively different portion of a boundary between the predetermined test target and the background; generating a signal related to the determined focus quality of the single captured image from the image sensor to a focusing station external to the digital camera module; and changing a position of a lens from the image sensor within the digital camera module to adjust a focus quality of subsequently captured images, wherein the determining of the focus quality of the single captured image includes analyzing the plurality of analysis regions, collectively defining less than 50% of the single captured image, exclusive of the remaining regions in the single captured image, and the determining of the focus quality of the image includes determining a variance of a spatial first derivative of the single captured image.