Abstract: This invention provides a method and system for increasing the bandwidth and distance of communication links by enabling noise from unwanted background radiation to be effectively eliminated. This is achieved by taking advantage of the fact that background radiation has much broader frequency spectrum than information signal carriers. Spectrum of interest is divided into multiple partitions. Reference signals are constructed over the spectral partitions according to defined selection criteria so that these reference signals can be used to reduce in-band noise of desired information signal through common mode noise elimination. Using differential signaling schemes further reduces noise from non-background radiation sources in addition to noise from background radiation sources. This method is applicable to both analog and digital systems.

Abstract: A method and apparatus used therein for modifying and enhancing the color, tonal range, highlight and shadow detail of an optical image, photograph, or photographic transparency in which the image to be enhanced is formed as a collection of small areas, called fields; the intensity and filtration of each field is independently adjustable for the purpose of achieving the desired enhancement of the image. In one embodiment, a photographic transparency is positioned in the front of a uniformly diffused light source. A video camera receives the image, transmitting it to a video tape recorder (or other device capable of single frame storage) through a special effects generator that can provide intensity and contrast control of the image, either positive or negative. The single frame is then displayed on a cathode ray tube (CRT) which has a diffuser positioned between it and the source transparency. The resultant modified, enhanced image is then photographed.