Patent ID: 6345117
Filing Date: 2002-02-05
Classification: H04N

Abstract:
A method for optimizing rap selection for correcting for separation misregistration in color printing of a color image having at least two input colors (C1,C2),a) generating a list of all unique colors appearing between colors (C1) and (C2) by processing all possible substitutions of a separation in color (C1) with a separation in color (C2); b) sorting said list into an array of vectors considering two separations equal if they differ by less than a predetermined tolerance with an integer value assigned to each of said colors in said array thereby forming for each array entry an associated CMYK(C1,C2) color; c) converting each element in said array of CMYK(C1,C2) colors from device coordinates into LAB-Vectors of device dependent color space each representing a list of possible misregistration of colors (C1,C2) in LAB-space; d) constructing a visibility vector(C1,C2) for each input color (C1,C2) and for each element in said LAB-Vector computing a difference value from color (C1) and from color (C2) for that element and storing the minimum of these two differences corresponding to the visibilities of all of said misregistration colors; e) for each entry in said visibility vector, if a maximum entry in said visibility vector is less than a threshold â€˜tâ€™ then the corresponding misregistration will not be visible and no action need be taken at (C1, C2) otherwise if the maximum is greater than threshold â€˜tâ€™ a candidate color for trapping is selected from a predetermined set of trapping colors maintained as a palette; and f) determining if the visibility of said candidate color for trapping is worse than the initial misregistration visibility of step (d), and if so, then no trapping color is selected.