The color description file of the device is in the middle of color management. The description file has representative color features of each device, such as characterization curve of chromaticity, characteristic curve of transmission gamut, etc. The color management system uses these representative The color feature completes the matching and conversion of the color spaces of each device. Color management requires a series of polite operational processes to achieve the desired consequences. Color management is divided into three methods in principle, which is referred to as [3C", namely calibration, characterization and conversion. Calibration: To ensure invariance and sustainability in the color information transfer process, input, display, and output devices are required to be calibrated to ensure they are in a standard duty profile. Input the correction of the brightness, contrast, and the quarrel field of the calibration scanner. In order to guarantee a consistent original, no matter what time division scan, the same image data should be obtained. The color is accurately displayed by setting the brightness, contrast, color temperature of the display, and the Gamma value of the entire display system. The output calibration corrects the calibration of the printer, the imagesetter, the printer, and the proofer, and corrects the characteristics so that the device can output according to the factory standard features. Characterization: Recording all the corrected features of the device is the process of characterization. These feature description files are bridges from the device color space to the standard device-independent color space. Conversion: Based on the calibration of the system equipment, the device is used to describe the file, and the standard device-independent color space is used as a preface to complete the precise conversion between the color spaces of each device. Since the color gamut of the output device is narrower than the color gamut of the original, the scanner, and the display, the color gamut is required to be shortened during color conversion, and the color gamut is shortened. In the ICC, there is an absolute chromaticity method, a relative chromaticity method, Four methods of convex saturation method and sensory method.