Real-time object boundary tracing circuit based on FPGA

The ordered boundary of the object is very useful information for shape analysis and calculating geometric features. In this paper, we presents a special circuit to trace the boundary of the object in real-time. The circuit can trace the boundary clockwise ordered and store the whole boundary position in memory. This circuit is implemented in a FPGA using VHDL. The circuit can process VGA resolution image over 60 times in one second using 24MHz pixel clock. The maximum frequency of pixel clock is 46.24MHz, so it can process VGA resolution image up to 109 fps. The size of the circuit is 6% of XC3 S5000. That makes it possible to implement other circuits for higher level processing on same chip.