CMOS image sensor that outputs Walsh-Hadamard coefficents
Yang Ni · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1998
Waish-Hadamard transformation is one of the most interesting linear transformations in image processing domain. The particularity of Walsh-Hadamard transformation is that it uses a set of basis functions which contain only +1 and -1, this results in a direct and simple computation without multiplication. This simplicity can not only reduce the complexity of the conventional digital processing unit, but also make possible some special rn-sensor cellular computation. This paper presents an original CMOS image sensor which can output directly the coefficient Waish-Hadamard of the sensed image. When the pixel i,jis addressed, it outputs the coefficient ij of the transformation Walsh-Hadamard instead of the gray level of pixel ij in a conventional image sensor. This image sensor has the following advantages : 1 0 gray level image can be reconstructed from partially read coefficients. This permits possible exchange between sensor output bandwidth and reconstructed image resolution, for example only quarter of coefficients can give a pretty good image; 2° some transformation based algorithms such as pattern recognition, image compression, etc. can use directly the sensor output without any hardware/software cost.