An edge detection filter comprising an array of filter coefficients having an odd number of rows and columns, a first set of zero coefficients extending along a direction traversing the array through a center position to form a first and second side, a second set of positive coefficients extending away from {HEAD ~ the direction} on {TAIL ~ the first side}, and a third set of negative coefficients extending away from the direction on the second side 
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An edge detection filter comprising an array of filter coefficients having an odd number of rows and columns , a first set of zero coefficients extending along a direction traversing the array through a center position to form a first and second side , a second set of positive coefficients extending away from { HEAD ~ the direction } on { TAIL ~ the first side } , and a third set of negative coefficients extending away from the direction on the second side
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