A new foveated space-variant camera for robotic applications

Abstract

A foveated camera has been designed and fabricated. The camera is implemented using a new foveated CMOS sensor which incorporates a log-polar transformation. This transformation has specially interesting properties for image processing including the information selective reduction and some invariances. The structure of this sensor permits an individual access to each pixel, exactly in the same way that the access to a RAM. This is a very interesting property that makes a big difference between a CCD based camera and a CMOS based camera. In the other hand, the CMOS nature of the sensor implies a very important fixed pattern noise due to the mismatch of the cell transistors. A fixed pattern noise correction circuitry has been included in the camera, in order to achieve a good image quality. The solutions adopted for achieving a low noise/signal ratio are also presented. Finally, some guidelines for including this camera in an autonomous navigation system are shown. The easy way for calculating the time-to-impact through this camera suggests the utilization of this sensor system for real-time applications.