Transformation of focus profiles for digital autofocus

A focus profile model is used to estimate the in-focus lens position so that a sharp image or video can be captured. In this paper, we propose an approach that transforms a wide variety of focus profiles generated by different focus measurement techniques into an analytic form and thereby converts the search of in-focus lens position into a mathematically tractable problem, resulting in a wide effective range and efficient image acquisition. An important feature of the approach is that it does not require any knowledge of the focus measurement technique used in a camera. Experimental results, including demo videos, are provided to demonstrate the effectiveness of the approach.