A fast focus measure for video display inspection

Abstract.

In this paper, we propose a robust and computationally fast focus measure for cathode ray tubes (CRTs) found in TVs and computer and video monitors. The focus measure is represented by the area ratio of a predetermined object pattern in the test image of a fixed size, which increases in size as the degree of defocus increases. The area ratio is calculated using a simple, straightforward moment-preserving method. On-line, real-time application of focus adjustment can be realized with the proposed method.