Brightening the Optical Flow through Posit Arithmetic
Vinay Saxena, Ankitha Reddy, Jonathan Neudorfer, John Leroy Gustafson, Sangeeth Nambiar, Rainer Leupers, Farhad Merchant · 2021
As new technologies are invented, their commercial viability needs to be carefully examined along with their technical merits and demerits. The positTMdata format, proposed as a drop-in replacement for IEEE 754TMfloat format, is one such invention that requires extensive theoretical and experimental study to identify products that can benefit from the advantages of posits for specific market segments. In this paper, we present an extensive empirical study of posit-based arithmetic vis-à-vis IEEE 754 compliant arithmetic for the optical flow estimation method called Lucas-Kanade (LuKa). First, we use SoftPosit and SoftFloat format emulators to perform an empirical error analysis of the LuKa method. Our study shows that the average error in LuKa with SoftPosit is an order of magnitude lower than LuKa with SoftFloat. We then present the integration of the hardware implementation of a posit adder and multiplier in a RISC-V open-source platform. We make several recommendations, along with the analysis of LuKa in the RISC-V context, for future generation platforms incorporating posit arithmetic units.