Patent Document ID: 20150317770
Application ID: 14269990
Patent Status: 0

Claim One:
1. An apparatus for determining defocus direction from an image, comprising: (a) a processor configured for processing an image which has been captured from an image capture element or device; and (b) programming executable on said processor for determining defocus direction of the image, said processing comprising: (i) partitioning the image into blocks; (ii) converting a spatial image function of each said block of the image into a frequency domain function, and convolving with a point spread function (PSF) while finding frequency pairs in the PSF with largest differences in transform magnitude; (iii) averaging transform magnitudes at the same radial distances to their origins, thus converting a two dimensional frequency domain function into a one dimensional frequency domain function; (iv) determining one or more pairs of local minimums in the one dimensional frequency domain function; and (v) determining a frequency difference feature as a ratio between radial components of the transform within said one or more pair of minimums to indicate in-front or behind position of the image in relation to a correct focus position for that image.