AN INVESTIGATION OF METHODS FOR DETERMINING DEPTH FROM FOCUS

The concept of depth from focus involves calculating distances to points in an observed scene by modeling the effect that the camera's focal parameters have on images acquired with a small depth of field. This technique is passive and requires only a single camera. The most difficult segment of calculating depth from focus is deconvolving the defocus operator from the scene and modeling it. Most current methods for determining the defocus operator employ inverse filtering. This paper will reveal some fundamental problems with inverse filtering: inaccuracies in the finding the frequency domain representation, windowing effects, and border effects. A general, matrix-based method using regularization will be presented, which eliminates these problems. The new method will also be confirmed experimentally, with the results showing an rms error of 1.3%.