| 摘要 |
PURPOSE:To enlarge the number of gradation steps able to be expressed by using both the area gradation method and the variable-dot gradation method. CONSTITUTION:For simplification of explanation, supposing that, e.g. an image data Dn is 4 bits [0-16 gradations], the number of ink drops [maximum value signal] Sn for obtaining the maximum value of density in a divided small area is equal to 4 and the dot matrix Mx is 2X2, the image data Dn input to a subtracting circuit 1 is divided by the maximum value Sn, whereby the quotient is Q' with the remainder R. Since Dn is '0-16' and Sn is '4', the quotient Q' is '0-4' and the remainder R is '0-3'. '1' is added to the quotient Q' by an adder 2 at the next stage. The corrected Q becomes '1-5'. Then, the corresponding matrix Mx is selected on the basis of the value '1-5' of the quotient Q from the 5 dot matrix patterns prepared beforehand. Accordingly, a factor Mn=0,1 or 2 of a divided small area corresponding to a recording position of the image data Dn is output. |
