Abstract: An overhead optical scanner is disclosed which uses commerical 60 Hz AC powered fluorescent lighting apparatus to illuminate the scanned objects. The image sensor of the scanner operates at a line scan rate which is in sync with the 60 Hz rate. The image sensor integrates the variations in illumination intensity received from the object over one complete 60 Hz cycle, thereby producing an electrical signal which is characteristic of a uniformly illuminated object.

Abstract: A dynamic gain adjusting arrangement modifies video signals produced by image scanners to achieve high quality pictures. The arrangement compensates for amplitude distortions of the video signal caused by lens vignetting and variations in lighting conditions. The video signals are compensated for these distortions by applying continuous gain adjustment to video information generated by a photosensor and by dynamically changing the gain adjustment parameters on a line-by-line basis according to an input signal reflecting the instantaneous background level.

Abstract: A flickerless video display for a gray scale image is obtained using binary picture elements in an interlaced field format. The flicker is eliminated by causing each display point on a line of the interlaced field to be vertically paired with and have an intensity equal to a display point which is located on an adjacent line. Incorporating this arrangement into a display system involves a modification only to the transmitter.

Abstract: A scheme for digitally encoding continuous-tone information from an original pictorial image includes processing electrical signals via separate networks (20,30) to generate (a) high-resolution detail data of "black" and "white" pels, and (b) low-resolution gray-scale or background data approximating the grayness of two-dimensional blocks (104) of pels (102).In the gray-scale network (30), the electrical signals are first compared (31) to different position-dependent threshold values to generate a binary signal (108) of black and white pels which represents gray-scale. Then, any of the pels (102) determined "black" in the detail network (20) are subtracted (36) from the gray-scale binary signal to generate a modified gray-scale binary signal (110). The black pels in the modified gray-scale binary signal for each block (104) are counted (42), the count approximating the background gray level of each particular block (104) of pels (102).