Digital restoration of blurred photographs

The amount of information that a human observer can obtain from a blurred photograph can be increased by post-processing the image in a digital computer. A complete procedure for restoring (by Wiener filtering) high-resolution photographs degraded by several common types of blurs is described. The practical aspects of obtaining an acceptable restoration are considered in detail. These include the limitations of the Wiener filter, the characteristics of photographic film and methods to identify the blur by analyzing the blurred image using only limited a priori knowledge. High-resolution photographs degraded by motion and focus blurs introduced directly in a camera are restored to illustrate the techniques.