The Research Of Equation From L～*a～*b～* To CMYK

During the printing engineering, monitor shows the color which is from RGB Space. However, printer and printing press use the color from CMYK.If the color information is expected to transfer from input device to output device accurately, it must be coverted from RGB into CMYK. However ,both RGB and CMYK are device-dependent color space,there is not only one way to show the color by RGB or CMYK.If there are more then one input device or output device,conversion will be very complex.Therefore a sort of device-dependent color space can be choosed as medi-color-space. Firstly, the color space of input device is coverted into the medi-color-space, then the medi-color-space is coverted into the color space of input device. L*a*b* Space is device-dependent uniform color space that ICC recomment to the world. L*a*b* Space can express all the visible color, it's gamut is the broadedt and it can include RGB space or CMYK space. Thus, L*a*b* Space can be as the conversion bridge from RGB into CMYK.The article will simply introduce the concept of color space and color management system. The keynotes are the establishment of mathematical conversion model from L*a* b* to CMYK and the test and verification of the precision of mathematical conversion model. It is the basis of establishment of our own color management. I have accomplished some following tasks:(1). Testing the plane theory advanced by Japanese scholar by color bar in IT 8.7/3 as sample data;(2). Adopting the method of regression to work out coefficient of plane equation, and establishing three-color mathematical conversion model.(3). Testing the precision of mathematical conversion model.(4). Acquiring four-color mathematical conversion model which is based on the three-color mathematical conversion model.