Hexagonal Image Sampling: A Practical Proposition

Abstract

A case is made for the use of regular hexagonal sampling systems in robot vision applications. With such a sampling technique, neighbouring pixels reside in equidistant shells surrounding the central pixel and this leads to the simpler design and faster processing of local operators and to a reduced image storage requirement. Connectivity within the image is easily defined and the aliasing associated with vertical lines in the hexagonal system is not a problem for robot vision. With modern processors only a minimal time penalty is incurred in reporting results in a rectangular coordinate system, and a comparison between equivalent processing times for hexagonal and rectangular systems implemented on a popular processor has shown savings in excess of 40% for hexagonal edge detection operators. Little modification is required to TV frame grabber hardware to enable hexagonal digitisation.