Patent ID: 8294964

Claim:
A computer implemented method for performing a CMYK to CMYKK p RGB color transform in a color marking device capable of dot-on-dot printing, the method comprising: receiving, from an image input device, an input percentage coverage c i , m i , y i , and k i , of each channel of said image input device; determining a minimum amount of composite-K coverage, k min , comprising: max(0,(c i +m i +y i +2k i −200); determining a maximum amount of composite-K coverage, k max , comprising: min(min(c i ,m i ,y i ), max(0,(0.5*(c i +m i +y i +k i ))−50)); determining an amount of a flexible composite-K coverage, k p , comprising: k min +α·(k max −k min ), where α is a function of said input values c i , m i , y i , and k i ; determining an amount of a remaining coverage area for each of c 1 , m 1 , and y 1 comprising: c 1 =c i −k p ; m 1 =m i −k p ; and y 1 =y i −k p ; determining an amount of a total coverage area of a secondary color RGB dot, rgb_area, comprising: rgb area=max(( c 1 +m 1 +y 1 )−100 +k i +k p ,0); determining each of an output secondary color value, comprising: b=rgb area−min( y 1 ,rgb area); r=rgb area− b −min( c 1 −b, rgb area− b ); and g=rgb area −b−r; determining each of an output primary color value comprising: c=c 1 −b−g; m=m 1 −b−r; y=y 1 −r−g ; and k=k i ; and providing said c, m, y, k, k p , r, g, and b values to a halftoning algorithm.