Abstract: Interpolation processing of digital map imagery data is carried out by prefetching full and half resolution data stored in half-resolution addresses of scene memory into a cache and accessing the cache as virtual addresses associated with the interlaced scan of the display are generated. Both full and half-resolution data is controllably weighted and summed bi-linearly to obtain interpolated data values for spatial locations corresponding to the virtual addresses. For a respective half-resolution storage location, stored imagery data includes both half-resolution data, (such as that representative of color characteristics, elevation, cultural features, linear and area features) of its associated half-resolution spatial location in a terrain map and a plurality of full-resolution data for a plurality of full-resolution spatial locations of the terrain map that are located in a adjacent neighborhood surrounding the half-resolution spatial location.

Abstract: A scheme for compressing and reconstructing multi-color high resolution navigation image data, such as aeronautical chart images provides an effective bit rate of one bit per pixel. Data representative of the image of a color aeronautical chart is sampled for a plurality of aerial grid points of the image (corresponding to pixels of the displays) each sample being digitized to provide an original color-representative matrix of data points, each resolved to some number of digital bits per basic color, per sample point. The color data is transformed into data representative of luminance (Y) and in-phase and guadrature chrominance (I, Q) components thereof. The Y, I, Q values are compressed using a clustering process that produces, for an aeronautical chart, sixteen clusters of combinations of colors and shades in the Y, I, Q domain.