A reflective rotund lens is positioned for projecting a panoramic picture of its horizontal surroundings at a given elevation onto a CCD array, for converting the picture into "pixel form" or an image signal. The image signal is digitized via an A/D converter circuit. A digital signal processor system is programmed for extracting a strip of pixel locations representative of an image ring mapped to pixel locations via superimposition upon the image, whereby all pixel locations outside of the image ring are eliminated by passing the pixels thereof through said A/D converter circuit at a rate higher than the conversion rate of the A/D converter circuit.