Patent ID: 8421906

Claim:
A method for selecting a focus setting for a digital image acquisition appliance, the method comprising: acquiring a first image with a first focus setting; acquiring a second image with a second focus setting, the second image being acquired sequentially with the first image; dividing the first image into a first grid of macroblocks; dividing the second image into a second grid of macroblocks; determining a first zone in the first grid of macroblocks and a second zone in the second grid of macroblocks using a first predetermined selection criteria, wherein the first predetermined selection criteria comprises the number of saturated macroblocks in the respective zone and in a macroblock order around the respective zone; calculating a macroblock shift of the first zone with respect to the second zone to a sub-macroblock precision; calculating a first value of a figure-of-merit for the first image and a second value of the figure-of-merit for the second image, the first value being calculated using focus metric data obtained from macroblocks belonging to the first grid of macroblocks, the second value being calculated using focus metric data obtained from macroblocks belonging to the second grid of macroblocks, wherein the calculated first and second values have been corrected for the macroblock shift; selecting the focus setting using a second predetermined selection criteria based on the first and second values of the figure-of-merit, wherein the second predetermined selection criteria comprises a maximum sum of squares difference (SSD) and/or a sum of absolute difference (SAD).