1. An apparatus for real-time modification of a natural scene for a human observer, said apparatus comprising: a camera for providing an image of the natural scene; a digitizer coupled to said camera, said digitizer receiving said image and operative to provide a digitized image having a plurality of pixels of said natural image; a plurality of digital filters each coupled to said digitizer to receive said digitized image of said image, each of said plurality of digital filters having a unique center frequency and each of said plurality of digital filters operative to provide a filtered digitized image; a threshold module coupled to said plurality of digital filters and receiving the plurality of filtered digitized images therefrom, for each of the plurality of filtered digitized images the threshold module operative to depict a pixel by a light scale when said pixel has an absolute value that is greater than a predetermined threshold and said pixel has a positive amplitude, to depict a pixel by a dark scale when said pixel has an absolute value that is greater than a predetermined threshold and said pixel has a negative amplitude, and depicting the remaining of said pixels in a gray scale; a contour module coupled to said threshold module and receiving said plurality of thresholded pixels, each corresponding to one of the plurality of filtered digitized images, the contour module operative to form a contour image by depicting a pixel in said contour image by a light scale if each corresponding pixel in each of the plurality of thresholded filtered digitized images is represented by a light scale, depicting a pixel in said contour image by a dark scale if each corresponding pixel in each of the plurality of thresholded filtered digitized images is represented by a dark scale, representing all remaining pixels as a gray scale, and providing a contour image of the thresholded filtered digitized image as an output.