Abstract: An image is scanned and dither processed in picture element groups of predetermined size, each corresponding to a group of cells of a remotely located display panel. As each picture element group is scanned, the pattern represented by the corresponding dithered image bits is compared to a dictionary of patterns stored in a first memory. If the pattern is not among those then in the memory, it is assigned an associated code word and is entered into the memory. In addition, both the pattern and its code word are transmitted to the remote location. They are there stored in a second memory, and individual cells of the cell group corresponding to the scanned picture elements are energized in accordance with the pattern. If, on the other hand, a scanned pattern is the same as one already stored in the first memory, only the code word associated with that pattern is transmitted to the remote location.

Abstract: Bi-level display systems capable of presenting gray-scale images are adapted for brightness and contrast control by circuitry which varies the means and deviation of the threshold values assigned to the cells of the display panel.

Abstract: The gray-scale information in a scanned image is presented on a bi-level display medium illustratively using the known ordered dither technique. In particular, the image is scanned in a matrix of picture elements, each corresponding to a different cell of the display medium. A dither threshold value is assigned to each picture element from a predetermined dither matrix. If the intensity of any given picture element is greater than the dither threshold value assigned thereto, the corresponding display cell is turned on. Otherwise, it is maintained off. The state of the cell corresponding to each picture element is represented by a dithered image bit. The bandwidth and/or time required to transmit the image to a remote display medium is substantially reduced by assembling in respective groups dithered image bits which correspond to picture elements having equal (or substantially equal) assigned dither threshold values.

Abstract: The random cell scintillations which have been observed in animated dithered displays are substantially eliminated by establishing a hysteresis band about the dither threshold value assigned to each display cell. The hysteresis band is delimited by upper and lower dither threshold values. Determination of whether the intensity of each picture element of the image to be displayed is to be compared to the upper or the lower threshold value assigned to the corresponding display cell is made based on the current state of the cell.

Abstract: The flicker which results when an ordered dither image is displayed in an interlaced-field format is eliminated by energizing each display point of the interlaced-field display to have an intensity proportional to the average intensity of a cluster of (illustratively four) cells of the dithered image rather than the intensity of a single one of the cells.

Abstract: Dithered display systems are adapted to present animated images via a conditional replenishment technique. The only cells of the display panel which are accessed for any given frame are cells which are to have states in that frame which differ from their respective states in the previous frame. Additionally, random scintillations in animated dithered displays are substantially eliminated by establishing a hysteresis band about the dither threshold value assigned to each display cell. The hysteresis band is delimited by upper and lower dither threshold values. Determination of whether the intensity of a given picture element of the image to be displayed is to be compared to the upper or the lower dither threshold value assigned to the corresponding display cell is made based on the current state of the cell.