ABSTRACT
Although there are algorithms that will effectively simulate a defocus operation on an image, most software packages don ’ t have them, so the diligent
digital compositor must resort to a blur operation. At first glance, under most circumstances, a simple blur seems to simulate a defocus fairly well. But in fact it has serious limitations, and under many circumstances, the blur fails quite miserably. This section explains why the blur alone often fails and offers more sophisticated approaches to achieve a better simulation of a defocused image, as well as methods for animating the defocus for a focus pull. Sometimes the focus match problem requires an image to be sharpened instead, so the pitfalls and procedures of this operation are also explored.
