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mitemitreski / javasurf

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Assymetrical convolution #2

Open GoogleCodeExporter opened 9 years ago

GoogleCodeExporter commented 9 years ago 
First notice that when computing IntegralSquare, point A is excluded and point 
D is included (you got sum(pixel) for x>xA && x<=xD && y>yA && y<=yD)

This is fine because point coordinates are computed using (int)(x-scale) for 
point A and (int)(x+scale) for point D resulting in truncation (except if scale 
if an integer value).

Looking at HAARConvolution.makeConvolutionDx for example, we can see that the 
width of the positive wavelet is 1 pixel greater than the width of the negative 
one. This is because the positive wavelet include the pixels values for the 
center of the filter. This is not good as the filter there is 0.

Suggest to modify code as follow:

  return (  integralImage.getIntegralSquare(x1, y1, x2-1, y3) 
          - integralImage.getIntegralSquare(x2, y1, x3, y3));

Same comment for other methods in HARRConvolution and GAUSSConvolution.

Original issue reported on code.google.com by yves.cui...@gmail.com on 1 May 2011 at 10:24