PURPOSE: To reduce the unevenness of density by overlapping inks with different densities each other by a method wherein density data are N-ary coded per pixel and one ink, which corresponds to the N-ary coded value on each pixel among n-1 kinds of different densities of same color-based inks, is jetted.
CONSTITUTION: Respective color processings are applied in a masking circuit 40 and an under-color removal and black forming circuit 41 to original image density signals Y1, M1 and C1 in order to produce image density signals Y36, M36, C36 and K36. Further, in a γ-correcting circuit 42, γ-correction is performed so as to input obtained image density signals Y37, M37, C37 and K37 in a ternary coding circuit 53 in order to ternary code the multivalued density signals Y37, M37, C37 and K37 in 0, 0.5 and 1. After that, when the ternary coded value is 0, the jetting signals of deep and light inks of respective colors are made to be 0. When the ternary coded value is 0.5, the jetting signals Yu48, Mu48, Cu48 and Ku48 of light ink are made to be 1. Further, when the ternary coded value is 1, the jetting signals Yk48, Mk48, Ck48 and Kk48 of deep ink are made to be 1 during printing.
HIRABAYASHI HIROMITSU (JP)
TAJIKA HIROSHI (JP)
SUGIMOTO HITOSHI (JP)
AKIYAMA YUJI (JP)
KANDA HIDEHIKO (JP)
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