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Color fundamentals for digital imaging
Published in Sharma Gaurav, Digital Color Imaging Handbook, 2017
For proper color reproduction, the input and output devices involved must be calibrated. Historically, the systems used for color reproduction were calibrated† in a closed-loop configuration. As shown in Figure 1.35, in a closed-loop configuration, the complete system is calibrated from input through output. Thus, for color photography, the film sensitivities, dye absorptances, and developmental interactions were appropriately chosen so as to result in acceptable reproduction. In offset printing, the scanner was used to generate CMYK “separations” that were suitable for generating halftone prints. With the increased use of digital computers and the evolution of desktop printing, it became obvious that such an approach has severe limitations. In particular, as the number of devices increases, calibrations for each input−output device pair are difficult to construct and maintain. In addition, because the calibrated data in a closed-loop calibration scheme are specific to one output device, they are not suitable for archival purposes or exchange with devices outside the system.
Underwater image restoration using level adjustment and colour equalization
Published in Journal of Modern Optics, 2022
Peng Yang, Heng Wu, Shaojuan Luo, Lianglun Cheng
To further verify the advantages of the proposed method, we qualitatively compare the proposed method with eight existing methods. Figures 7–12 present the experimental results under the bluish, greenish, cyan, light, yellow and light green environments, respectively. Intuitively, the background color seriously affects the visual quality of underwater images. Traditional methods usually only consider one aspect, such as CLAHE can effectively improve contrast, but cannot remove stains. DWBE can enhance underwater green images by complementing red light, but it doesn't work well in other underwater environments. ULAP can enhance the underwater green image, but the enhancement performance for the blue underwater image is poor. UDCP exacerbates the effects of color casts. The dehazing performance of RGHS is good, but the color reproduction performance is not outstanding. The performance of IBLA is opposite to that of RGHS. Compared with other eight methods, the proposed method can improve visual effects in different underwater scenes and can still work when other methods fail. The results in Figures 6–12 demonstrate that the proposed method has good underwater restoration performance and generalization ability.
Tutorial: Background and Guidance for Using the ANSI/IES TM-30 Method for Evaluating Light Source Color Rendition
Published in LEUKOS, 2022
Besides general guidance on factors that might influence the choice of specification criteria, Annex E provides recommended criteria for three design intents with three priority levels (i.e., criteria restrictiveness) that are applicable at typical interior light levels (200–700 lux) when the space illuminated features a variety of colors. The design intents include: Color Preference (P): Intent to create a pleasing, natural-looking environment. Color Preference could be the dominant color rendition design intent in retail, office, hospitality, or residential lighting applications.Color Vividness (V): Intent to create a vibrant scene, regardless of whether that is natural-appearing or not. Color Vividness could be the dominant color rendition design intent in specific entertainment, display, or retail lighting applications.Color Fidelity (F): Intent to achieve similar color appearance, at equal illuminance levels, to the reference illuminant. Color Fidelity could be the dominant color rendition design intent in manufacturing, medical, color matching, or color reproduction lighting applications.
The characteristic of image quality perception of elderly group: according to the comparison with adult group
Published in Journal of Information Display, 2018
In a study by Tremeau and Charrier [19], it was explained that the relationship between image color and image quality and between colorfulness and naturalness act as major factors in evaluating image quality. When the colorfulness of an image is adjusted according to the memory color at a similar level, the naturalness of the image increases and positively affects the image quality evaluation. As explained, the color reproduction and image quality preference of an image are closely related to memory color. Memory color tends to appear with higher brightness and saturation than the actual color [20–22]. In particular, the main feature of memory color is that its chroma/saturation is higher than that of the actual color [23,24]. Previous studies showed that the image quality preference increased when the saturation was adjusted to make it close to the memory color [25,26]. Especially, as the saturation increased to the level similar to the memory color, the tendency of image quality preference increased [27]. This characteristic of memory color was also manifested in the same manner on the display medium that reproduces color with light in an experiment conducted with an RGB monitor by Olkkonen et al. [28].