A Research Of Color Space Conversion And Model Establishment Of Output Device Of Prepress System

To establish the color management system in the prepress device, the same color information which transfer in different device should be lost the least. This need first the color gamut to be calibrated in various device, and in the base of the first step the consistency during the color transferring in different device could be provided by finding proper method for color space conversion and gamut mapping. So the research of finding method for color space conversion and gamut mapping of the prepress device will be meaningful to the perfect copy of the manuscript. Since LCD monitor and color ink jet printer are important output device of prepress system, it is the most significant and necessary work to investigate their characteristic.In this paper, starting from the requirement of color management, combining with LCD monitor and printer, on the basis of BP Neural Network theory and three-dimensioned lookup table with interpolation algorithm theory, by the establishment of device characteristic and device calibrated model and algorithmic of gamut mapping, color management of output device of prepress system was designed deeply in system with experiments and theory analysis. And the color management prototype system was built and carried out.In the base of the former research, BP Neural Network theory and 3D-LUT theory were firstly mentioned and used to establish the characteristic model and the calibrated model of LCD monitor and printer. In the base of the research and integration of the advantages and disadvantages of the former different mature gamut mapping method, an new color angle segmentation method had been put forward to improve chroma excursion method for gamut mapping. And the color target including 1000 modeling color blocks and 200 testing color blocks had been designed. In addition, in the consideration of the color character of different types of images, some bmp testing images had been designed for evaluation from personality. The color management prototype system was designed by using the soft plat of MatLab 7.0.According to the results, by using BP neural network and 3D-LUT, the precision of the device characteristic mode and calibrated model is improved from theory and practice. With the new color angle segmentation method, chroma excursion method could be improved from aspects of efficiency and precision. The precision of the model and the validity of the data was provided well to meet the need of asymmetry segmentation of the original color gamut by designing modeling color blocks and testing color blocks. According to the research, 5 layers BP neural network was designed for the characteristic model, tetrahedron 3D-LUT theory was designed for the calibrated model, and the improved chroma excursion method was designed for the gamut mapping model. The color management system which designed and carried out in MatLab 7.0 made the effect of soft proof well.