การผลิตซ้ำของภาพสีน้ำจากข้อมูลสเปกตรัมบนจอภาพซีอาร์ที / พรทิพย์ ถาวรยุติการต์ = Reproduction of water color images from spectral data on CRT displays / Pornthip Thavornyutikarn
Color Management Systems (CMS) have been used as a crucial tool in the reproduction of color on various devices In a predictable way. The device can be a monitor, scanner, printer, proofer, or press. The reproduction of color on these devices using only a few color data is inefficient to match color under different illuminations. On the contrary, the use of spectral data in the reproduction of color can satisfy the match in different devices and illuminations, as a result of its device independent data. This research studied the procedure of color reproduction in the Cathode Ray Tube (CRT) display exploiting the spectral data of a water color image. A color chart of 679 small rectangle patches was made using 35 tubes of water color with its single color or a mixture of two or three. The spectrum of these patches were measured and were used to investigate the optimum number of filters needed to capture water color painted images using the training set of 176 colors chosen from 679 colors. Five filters, bpb42 bpb53 bpn50 sc64 sc66, were used to capture the images therefore five sets of pixel values were obtained. The Wiener estimation method was used to estimate the spectral data from these pixel values. To reproduce the color on a CRT display, each pixel values was converted to XYZ values and subsequently RGB values. The calibration and characterization of the display were carried out and the spectrally reproduced images together with conventionally reproduced images (RGB digital camera) were subjectively and quantitatively compared to the original images. The yellow tone of spectral images was the most similar to the original image. In other color tones, the spectral images were not as good as conventional one. The averages of the color difference under D50 between measured color and estimated color of skin tone, leave tone and sky tone were 8.74, 10.15 and 6.88, respectively, and were 8.88, 10.16 and 7.02, respectively, under D65.
