Abstract: In a large area display system, multiple persons may work together with multiple input devices for supplying and receiving information in an interactive system with a single large area display. The large area display system comprises a screen wherein computer generated information is projected upon one side of the screen, and users interact with the computer from the opposite side of the the screen. Data coordinates for an input device corresponding to a pseudo image sensed by the receiving subsystem electronics are provided to the controlling computer. The input data coordinates from the pseudo image are normalized for variations due to frequency dependence and electronic drift. The normalized data coordinates are looked up in a calibration table to account for distortion in the pseudo image detection electronics. Screen coordinates corresponding to pixel locations on the large area screen are found by interpolation from the data From the calibration table.

Abstract: The contour fidelity of reproduction of images is enhanced by matching groups of pixels with templates based on a hierarchical set of patterns. This is accomplished by isolating a symmetrical window of pixels in the image including a central pixel and matching the groups of pixels in the window with hierarchical templates. Enhancement values for the central pixel are provided based on the results of the comparison. Windows are formed so that each pixel in the image is a central pixel for at least one window. The hierarchial set of patterns is developed so that each pattern in the hierarchy is a combination of an extension pattern and the pattern immediately below it in the hierarchy. This significantly reduces the hardware requirements for implementation of the technique. Templates are developed by creating horizontal, vertical, reversed and inverted permutations of each pattern in the set.