CALIBRATION METHOD FOR IMPROVING THE AUTOFOCUSING SPEED IN DIGITAL CAMERAS

摘要

The invention relates to a method characterised in that it comprises a first step of placing a calibration standard in front of the camera; in a second step, a sequence of images is captured by focusing the camera at different distances around the position of the standard; an intensity profile for the grey levels is extracted from each image of the calibration standard; for each profile, l(x) obtained, a value is estimated for the defocusing radius &rgr;, by adjusting the equation (1) to the corresponding profile: (1) where erf is the error function: (II) and the value of the camera constant is obtained by adjusting the curve of the values of the defocusing radius &rgr; according to the values of u, according to the following equation: (III).