Non-integer values in getPixel()

[sevbogae]

Hi,

I see that you use non-integer pixel positions to get the pixel values: xp =i+x0+0.5; yp =j+y0+0.5; When you use getPixel() on non-integer values, it will use interpolation. When you have a perfect edge [..., 0, 0, 255, 255, ...], the edge will be smoother because of this interpolation (see image, the real edge is just [..., 0, 0, 255, 255, ...], yet the ESF is [..., 0, 0, 127.5, 255, 255, ...]), resulting in worse MTF at the end.