Patent ID: 6215562
Filing Date: 2001-04-10
Classification: H04N

Abstract:
A method for calibrating a color printing device, such as a color printer, including the steps of:printing a first target layout, which includes graduated primary color toner or ink patches to detect a printing device's primary color start and end points and graduated black toner or ink circles to detect a printing device's percentage dot gain;comparing visually said primary color toner or ink patches and said black toner or ink patches and choosing the said primary toner or ink start and end points and said black toner or ink tone response;generating a black transfer curve using said black start and end points and said black tone response, thereby finding the function that compensates for the drift in the printing device;printing a second target layout, which incorporates said black transfer curve as background gray and includes patches of gray made of mixtures of primary color toners or inks such as for example cyan, magenta, and yellow inks (CMY);comparing visually said background gray with said CMY grays and choosing best match from said CMY patches;performing said comparison of background gray to CMY gray patches in an iterative process until acceptable match is found;generating transfer curves for primary toners or inks using above said start and end points and said black transfer curve, thereby finding functions that compensate for the drift of the primary colors of the printing device; andupdating each one-dimensional lookup table (LUT) with said compensating functions.