OFFSET INK PRINTING METHOD

PROBLEM TO BE SOLVED: To provide a printing method which enables the reproduction of a color range wider than a color reproduction range of RGB expressed by conventional four-color printing of yellow, red, indigo and black processes. SOLUTION: An offset ink printing method excellent in high-chroma color reproduction is characterized as below. In offset printing, either two or three of yellow ink, red ink and indigo ink, and black ink are used. A density value of yellow is in the range of 0.85-0.91; a density value of red is in the range of 0.88-0.94; and a density value of indigo is in the range of 0.84-0.90. When printing is done by singly using or superposing the respective color inks within the above ranges, chromaticity (JIS Z 8729) based on an L*a*b* colorimetric system, and chromaticity of overprinting using the two-color inks fall within specific ranges, respectively. Additionally, the yellow (a), the red (b) and the indigo (c) have specific reflection factors, respectively. COPYRIGHT: (C)2008,JPO&INPIT