In hardware implementation, there are different architectures that can represent the same algorithm into hardware. The different architectures are usually caused by using different number representations. In this work, two hardware architectures of optical flow constraint equation of Horn and Schunck (OFCE-HS) are presented and compared. The first architecture (OFCE-HS MZ) is previous work using full integer number to represent the architecture. The second architecture (OFCE-HS RH) is our work using combination between integer and fraction number to represent the architecture. Hardware designs of the architectures are performed using Xilinx System Generator through HW-SW co-simulation scheme. As a result, our proposed work has better performance compared to the previous work. It has the ability to reduce noise as well as hardware resources. © 2011 IEEE.