The Blur filter applied to a photograph
The simple Blur filter produces an effect similar to that of an out of
focus camera shot. To produce this blur effect, the filter takes the
average of the present pixel value and the value of adjacent pixels and
sets the present pixel to that average value.
Filter advantage is its calculation speed. It suits big images.
Filter disadvantage is that its action is hardly perceptible on big
images, but very strong on small images.