Abstract: A large set of image data values are associated with a smaller set of values, such as color palette look-up table (LUT) indices, to create an inverse table. The larger set of image data values address into the inverse table. The inverse table is simulated as a symmetrical N-dimensional structure in computer memory, with N being the color dimension of the image data values. Generally, a set of star spaces in the structure are captured by the color palette LUT indices; the capturing is based on some relationship such as the relationship between the image data values and the color palette values indexed by the color palette LUT indices. The remainder of the structure spaces are captured by performing a uniform and iterative expansion away from each star space, capturing each uncaptured space encompassed by the expansion until all spaces are captured.

Abstract: A trapping technique which accepts a Postscript or other page description language (PDL) file and outputs a file in PDL format having the correct traps. The input page is first divided into sub-portions, or tiles, and the tiles are individually processed by evaluating the input file in a corresponding clipping window. Each tile is then analyzed to determine where edges exist. The edge data is fed to an edge converter which produces a list of color transitions consisting of the analytic description of each edge and the color information along the sides of the edge. The color transition information is fed to a trapping analyzer which generates trap vectors in accordance with a set of desired trapping rules. The trap vectors are then converted to PDL form. As a final step, the trap vectors are added to the original PDL file. The final trapped page may be printed on standard typesetters without the need for special trap generator hardware.