با استفاده از یک برنامه کوچک به صورت عملی تفاوت دستورات fspecial disk و fspecial motion را نشان خواهیم داد.
هدف از مقایسه این دو فیلتر این است که بفهمیم کدام یک برای تار کردن تصویر مناسب تر است.
'disk' : Circular averaging filter (pillbox)
h = fspecial('disk', radius) returns a circular averaging filter (pillbox) within the square matrix of side 2*radius+1. The default radius is 5.
'motion' :Approximates the linear motion of a camera
h = fspecial('motion', len, theta) returns a filter to approximate, once convolved with an image, the linear motion of a camera by len pixels, with an angle of theta degrees in a counterclockwise direction. The filter becomes a vector for horizontal and vertical motions. The default len is 9 and the default theta is 0, which corresponds to a horizontal motion of nine pixels.
To compute the filter coefficients, h, for 'motion':
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Construct an ideal line segment with the desired length and angle, centered at the center coefficient of h.
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For each coefficient location (i,j), compute the nearest distance between that location and the ideal line segment.
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h = max(1 - nearest_distance, 0);
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Normalize h:h = h/(sum(h(:))
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