> removes those frequencies from an image that correspond to the size of halftone dots both horizontally and vertically And all the harmonics that make out the

> removes those frequencies from an image that correspond to the size of halftone dots both horizontally and vertically And all the harmonics that make out the circle shape. I'm pretty sure that making the circle repeat horizontally and vertically is some kind of convolution product and that has some nifty properties under Fourier transform.