Study on the Relationships between the Optical Printing Density Based on the Offset Overprint Trapping and Ink Film Thickness

The research finds out some existing certain regularity, and further revises the formula D = D (1- e - ml ). The formula means the relationship between ink thickness and ink in density. By using the formal of one-color ink thickness and ink density, the second density that correspond the first major density is transferred to the equal thickness. Then they are added together. According to the formula the real ink density is calculate. Then use the above formula to work out ink thickness. In this way, overprint densities come out, and make contrast with the actual measure data, so the new model formula is built up. The result shows that the average error between the overprint density calculated by ink thickness and the actual measure data is about 0.07. However, the average error between the calculated density using the simple adding method and the actual measure data is about 0.5, so this method is practical and more accurate.