Reseach On Eqation From L～*a～*b～* To CMYK～*

Satisfying increasingly requirements for consistency and predictability in the printed process, it is important to find a accurate and practical equation from L*a*b* to CMYK. The topic of this paper is to research the conversion from L*a*b* to CMYK, which is based on plane theory .The plane theory is first advanced by Japanese scholars .Not only is the color conversion the key in the color separation and color match, but also in the detecting the printed–paper directly and the digital press. Although the conversion has been developed quickly and some softwares which we have made use of it in practice (like Photoshop which is produced by Adobe , Foto Tune which is produced by Agfa and color sync which is produced by apple) in this aspect has been gotten some success in other countries, there is no great success in our country. So it is something of value in the theory and applied research to solve the problem of conversion from L*a*b* to CMYK.Firstly, I will explain the effect of color conversion in the CMS, in the color separation and color match, in the detecting the printed–paper directly and the digital press; analysis the present existed models from L*a*b* to CMY. Then The plane theory based on optic phenomena presented by a Japanese scholar is testified at first. Then the equation of transition from L*a*b* to CMY is modeled. Based on it, we get that the plane theory is suit for CMYK color space too and make the model from L*a*b* to CMYK. Soon its precision is discussed and the main reasons that influence the equation precision are analyzed . At last a more accurate equation from L*a*b* to CMYK is made.