ABSTRACT
Abstract-This paper examines a novel source of depth information: focal gradients resulting from the limited depth of held inherent in most optical systems. Previously, autofocus schemes have used depth of held to measured depth by searching for the lens setting that gives the best focus, repeating this search separately for each image point. This search is unnecessary, for there is a smooth gradient of focus as a function of depth. By measuring the amount of defocus, therefore, we can estimate depth simultaneously at all points, using only one or two images. It is proved that this source of information can be used to make reliable depth maps of useful accuracy with relatively minimal com putation. Experiments with realistic imagery show that measurement of these optical gradients can provide depth information roughly com parable to stereo disparity or motion parallax, while avoiding imageto-image matching problems.
