Nathaniel Joseph McCaffrey

BLINC: a 640x480 CMOS active pixel video camera with adaptive digital processing, extended optical dynamic range, and miniature form factor

A miniaturized camera utilizing advanced extended dynamic range CMOS APS imager technology and employing real-time histogram equalization has been developed for capturing scenes having high intra-scenic dynamic range. The camera adapts to changes in scene brightness and contrast in two frame periods, and acquires fully processed images in less than 100 milliseconds after power is applied. The BLINC camera contains an automatic exposure time control and is capable of capturing over 8 equivalent f-stops of optical dynamic range. This exposure time control along with programmable extended dynamic range and built-in 12-bit analog to digital converter allows the Sarnoff APS75 CMOS VGA image sensor to accommodate up to 15 f-stops of intra- scenic dynamic range. The APS75 sensor was fabricated with standard CMOS-7 design rules in a 0.5 micron SPTM process. Progressive scan digital video is stored and processed in real-time by an application specific integrated circuit image processor to provide optimal image contrast and exposure. The processed video is then transformed to 10-bits with a proprietary adaptive non-linear mapper before being converted to standard RS-170 analog video. Small size, light weight and low energy consumption make this camera well suited for UAV, and automotive applications.

Very low cost real time histogram-based contrast enhancer utilizing fixed-point DSP processing

A real time contrast enhancement system utilizing histogram- based algorithms has been developed to operate on standard composite video signals. This low-cost DSP based system is designed with fixed-point algorithms and an off-chip look up table (LUT) to reduce the cost considerably over other contemporary approaches. This paper describes several real- time contrast enhancing systems advanced at the Sarnoff Corporation for high-speed visible and infrared cameras. The fixed-point enhancer was derived from these high performance cameras. The enhancer digitizes analog video and spatially subsamples the stream to qualify the scenes luminance. Simultaneously, the video is streamed through a LUT that has been programmed with the previous calculation. Reducing division operations by subsampling reduces calculation- cycles and also allows the processor to be used with cameras of nominal resolutions. All values are written to the LUT during blanking so no frames are lost. The enhancer measures 13 cm X 6.4 cm X 3.2 cm, operates off 9 VAC and consumes 12 W. This processor is small and inexpensive enough to be mounted with field deployed security cameras and can be used for surveillance, video forensics and real- time medical imaging.