Tham khảo tài liệu 'recent advances in mechatronics - ryszard jabonski et al (eds) episode 2 part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 664 M. Kretkowski H. Suzuki Y. Shimodaira R. Jablonski estimated by least square sum analysis involving spectral data and values obtained from camera CCD sensor for each color reference. Introduction For accurate color reproduction there is a need of developing new tools for calibrating a digital camera system capable of reproducing high fidelity colors for telemedicine internet shopping industrial design and other high accuracy color reproduction demanding applications. The camera is equipped with three filters S1 S2 and S3 which correspond to red green and blue band. These filters have relative spectral sensitivity similar to primary color sensitive cones in human eye Fig. 1. . Macbeth ColorChecker Chart is used to determine numerical color description for reference. As an illuminant there is a CIE Daylight 65 D65 standard used. Under this certain conditions automatic method of calibration with use of an integrated spectrometer inside the camera based on a fiber optic measuring probe has been developed. Wavelength nm . Filter spectral characteristics. Measured color is represented by the tristimulous XYZ values 1 . Color captured by the camera is represented by S1 S2 S3 values corresponding to pixel value under each filter acquisition. To provide high fidelity color reproduction a conversion matrix between XYZ and S1 S2 S3 values must be obtained by means of least square sum analysis 2 . XYZ camera principle For total description of color there can be used so called tristimu-lous values XYZ 1 . A digital still camera with output containing these Automatic color calibration method for high fidelity color reproduction digital . 665 values supported by proper filters and equipped with internal spectrometer is able to reproduce high fidelity colors in the same way as human eye would perceive it. Figure 2 shows principle of the camera. Light passing through the lens is split by a semi-transparent mirror. Part of the light reflected by the mirror is used for .
