Linear quadtrees: A blocking technique for contour filling

摘要

Given a linear quadtree forming a region's contour, an algorithm is presented to determine all the pixels 4-connected to the border's elements. The procedure, based on a connectivity technique, associates a two-valued state (“blocked” or “unblocked”) with each node and fills increasingly larger quadrants with black nodes whose state is known to be unblocked. Advantages of the proposed procedure over existing ones are: (i) multiply connected regions can be reconstructed; (ii) the border can be given as a set of either 4- or 8-connected pixels.