The Research Of Equation Between L～*a～*b～* And CMY

With the people requiring the quality of presswork, Color Management System become more and more important, So it is necessary to research the problem of conversion between L~*a~*b~* and CMY.The plane theory and tetrahedron interpolation technology are used to achieve conversion between L~*a~*b~*and CMY on Flexography in this paper. First, the plane theory is introduced, and its applicability is proved. Conversion model is established by using mathematic method and the exactness is checked up. After that, considering the problem of conversion equation from L~*a~*b~* to CMY, author brings forward the method that tetrahedral partition technology to solve the color gamut volume enclosing the definition domain and partition of the gamut. The conversion model is established and the precision is verified. At last, the precision both of two methods are compared.The paper takes the color error in CIE1976 L~*a~*b~* equal color space as the standard, the method of plane theory is better than tetrahedron interpolation, the difference of the mean color error between two methods is 0.21, and the difference of the maximal color error is 0.04, in the conversion from CMY to L~*a~*b~*; and the paper takes some error standard of dot area coverage as the standard, the method of tetrahedron interpolation is better than the plane theory, the difference of dot area coverage standard error is 0.05%, 0.91%, and 0.22%, the mean error is 0.28% ,0.64%,0.43%, and the maximal error is 0.59%, 2.02%, 0.18%, in the conversion from L~*a~*b~* to CMY.The conclusion of this paper is of great value to the further research on CMS and has certain applied values in the publishing field. The technology of color conversion has a direct effect on the capacity of color reproduction.