Patent ID: 6515770
Filing Date: 2003-02-04
Classification: H04N

Abstract:
A method for preparing a dither mask calibrated to a printer P such that the printer can print an intended number d of distinct halftone levels without using a tone reproduction curve to produce calibrated halftones by the printer, the method comprising the steps of:preparing a master mask as a dither matrix D0 with some number of d0 of threshold levels, where d0 is significantly larger than d; constructing an approximation N1(M,P) of the image of the matrix printed by the printer P; determining which of the d0âˆ’1 values is closest to 1/d, 2/d, . . . , (dâˆ’1)/d and then selecting those values to be threshold values ti; and transforming the matrix D0 to a calibrated dither mask Dp adapted to printer P by setting Dp&af;(i,j)=mink&it;(tk&it;&LeftBracketingBar;tk&GreaterEqual;D0&af;(i,j)).