1. A method comprising: detecting edges in at least a region of a captured focus image, using adjacent pixels of said region to obtain first edge detection results; filtering said first edge detection results, the first filtering comprising: comparing differences in pixel contrast in said first edge detection results with a first threshold value; and removing said differences in pixel contrast that are less than said first threshold value from said first edge detection results; detecting edges in at least said region, using non-adjacent pixels of said region to obtain second edge detection results; and filtering said second edge detection results, the second filtering comprising: comparing differences in pixel contrast in said second edge detection results with a second threshold value; and removing said differences in pixel contrast that are less than said second threshold value from said second edge detection results.