High-speed multiple spatial band-pass filtering using a resistive network

In this study, we developed a vision system that separates an image into a set of spatial frequency bands using multiple spatial filters during each single frame sampling period of 20 ms. The vision system comprises active pixel sensors (APS), two sample and hold (S/H) circuits, an analog resistive network, and a field-programmable gate array (FPGA). The resistive network facilitates instantaneous spatial filtering where its spatial property depends on its resistance. We implemented a digital circuit in the FPGA, which controls resistance of the resistive network and the timing when reading out spatial-filtered images in a single frame. We examined the performance of this system by presenting a set of test images. The system output three spatial band-pass filtered images at 50 fps.