  The simplicity principle states that the human visual system prefers the
simplest interpretation. However, conventional coding models could not resolve
the incompatibility between predictions from the global minimum principle and
the local minimum principle. By quantitatively evaluating the total information
content of all possible visual interpretations, we show that the perceived
pattern is always the one with the simplest local completion as well as the
least total surprisal globally, thus solving this apparent conundrum. Our
proposed framework consist of (1) the information content of visual contours,
(2) direction of visual contour, and (3) the von Mises distribution governing
human visual expectation. We used it to explain the perception of prominent
visual illusions such as Kanizsa triangle, Ehrenstein cross, and Rubin's vase.
This provides new insight into the celebrated simplicity principle and could
serve as a fundamental explanation of the perception of illusory boundaries and
the bi-stability of perceptual grouping.
