A Video Real-Time Pyramid Processor
Roger F. Bessler · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1986
The pyramid is well suited for image enhancement since its' bandpass structure closely matches the human visual system and efficient because successively lower octave frequency bands are represented by proportionally fewer samples. The algorithm is also well suited for pipe-lined real-time video processing since each successively lower spatial frequency band is generated from its' predecessor using the same low-order filters. A prototype pyramid system was built to process off-air monochrome NTSC video in real-time at 30 frames-per-second. The system digitizes input frames into 512 horizontal samples per line and 48() vertical lines linearly quantized to 8 bits. It decomposes these images into 5 bandpass sub-images simultaneously using multiple cascaded 7-tap two-dimensional filters. The original image is then reconstructed from the bandpass com-ponents using the inverse process. The system is computer controlled allowing variation of internal parameters such as filter coefficients, filter kernel size, arithmetic precision, and number of bandpass images generated. The hardware is configured to allow simultaneous viewing of the input, 5 bandpass components, and reconstructed original image. Image enhancement operations, such as band optimized noise coring, can be added to the system as board level features in-line with the bandpass images' data paths prior to reconstruction. The complete pyramid system is modular, self contained, performs the real-time two-dimensional bandpass processing and will likely have impact on future television systems.