Color Research and Application最新文献

Color has become an essential element in our communication and our judgment on products. In textile, the formulation of any color is an essential process to ensure color continuity from the master standard to all subsequent production batches. Indeed, the objective is to normalize its reproduction all along the color reproduction procedure. In the literature, researches concerning textile color formulation are important, so this review focuses on these different techniques and methods of color matching for dye mixtures and precolored fiber blends. This step involves determining the dyes or fibers to use (alone or in mixtures) and their appropriate proportions to reproduce the wanted colors. The main techniques used for dye mixtures are based on colorimetric, spectrophotometric, and artificial intelligence techniques. While for precolored fiber mixtures the used techniques are dived into theoretical and experimental models. In addition to the review of these different techniques, a quantitative analysis was carried out.

Reproducing near-gamut colors on an emissive display often causes them to appear brighter than an achromatic color of the same luminance. This phenomenon can be explained by the Helmholtz–Kohlrausch (H–K) effect, which describes an increase in perceived brightness when increasing the chroma of a stimulus. Although recent studies have attempted to incorporate the H–K effect into their modeling, none of these studies have directly explored how the perception of chromatic stimuli changes with background luminance. In this article, we present results from a psychophysical brightness-matching experiment conducted across different levels of background luminance. The experimental results show the magnitude of the H–K effect upon simultaneous lightness contrast for high chroma colors. We, then, compare our results to CAM16 and other published models that propose modifications to CAM16 to account for the H–K effect. The findings reveal that CAM16 overestimates the perceived rate of lightness change by more than double for highly saturated, low luminance colors with increasing background luminance levels. Despite the progress made in incorporating the H–K effect into models, our study indicates the need for further data to establish a more accurate and robust modeling of this phenomenon.

Patients who undergo transcatheter aortic valve implantation (TAVI) may become pale during the early postoperative period. To clarify whether facial colors changed during the postoperative period, patients' skin color from before to 72 h after TAVI was measured spectrophotometrically. Factors associated with skin color were also investigated. Forehead skin color and vital signs were measured before TAVI and at 6, 18, and 72 h after TAVI in 11 patients scheduled for TAVI. Blood examinations were performed before and 18 and 72 h after TAVI. Skin color was assessed using a spectrophotometer and expressed as L* (lightness), a* (red/green), and b* (yellow/blue) according to the CIE1976L*a*b* color space. Skin lightness L* values increased at 6 and 18 h after TAVI and returned at 72 h after TAVI and a* values decreased at 6 h after TAVI. The b* values did not change perioperatively during TAVI. No associations were observed between the changes in skin color and changes in BP or laboratory data. The findings that the skin color became whitish and less reddish in the early postoperative period resembled that occurring during an acute inflammatory response. Observation of skin color is important to detect the possibility of postoperative complications.

Research suggested that color vision evolved for the purpose of seeing skin color modulations signaling emotion or mood. Hence people want to find the connection of the cone sensitivities with the skin spectral reflectance. In this article the W and V shapes based on skin spectral reflectance measured at different positions and from different ethnic groups (Kurdish, Caucasian, Thai, Chinese) were investigated. First, it was found that the measured skin spectral reflectance from all body positions and ethnic groups have a V shape between 400 and 450 nm and a W shape between 520 and 610 nm. The W and V shapes from the measured skin spectral reflectance are clearly different from those from the spectral reflectance generated from the physical model. The V shape and W shape do not exist with spectral reflectances measured from artificial skin color. Second, it was found that the wavelengths where the left trough assumes for the W shape are different from the wavelength where the M cone peaks, and the wavelengths where the central peak of the W shape assumes are different from the wavelength where the L cone peaks, which are different from the results from literature. Third, it was found that the skin spectral reflectance varies with body positions and ethnic groups. The W shapes turn to be a “U” shape for the spectral reflectance measured at back of the hand and inner forearm positions. The spectral reflectance measured from Kurdish starts decreasing for each body positions for wavelength greater than 700 nm, which is clearly different from the spectral reflectance measured from the Chinese and Caucasian ethnic groups. The findings of this paper are valuable for improving the physical model for generating skin spectral reflectance, reconstructing skin spectral reflectance based on image, identifying human skin color from spectral imaging and rendering of human skin color in computer graphics.

When we enter a dark place, such as a tunnel, from a bright exterior, our visual sensitivities take some time to adapt to lower light levels. However, there have been few reports on how quickly luminance and chromaticity discrimination sensitivities recover in this situation. This study aims to quantify the time course of discrimination sensitivity for luminance and chromaticity directions after an abrupt decrease in background luminance. In each trial, the background luminance was decreased from 100 to 1 cd/m². Subsequently, one target and three reference stimuli of different colors were presented under four stimulus-onset asynchrony (SOA) conditions. The participants discriminated the target stimulus from reference stimuli. The results showed that discrimination sensitivity was the lowest right after the background luminance changed and gradually improved with SOAs. The sensitivity decreases differed across color directions, with the greatest decrease in luminance, a moderate decrease in S−(L + M), and a negligible change in L−M. However, statistically significant differences were observed only between luminance and L−M, suggesting that the sensitivity decrease after the abrupt decrease in background luminance did not significantly differ between the chromaticity directions. We speculate that these results stem from the interaction between chromatic perception and luminance adaptation, and possibly from rod intrusions.

This study aims to identify the color preferences of ancient Egyptian paintings and their cultural and historical reasons through color analysis, and consequently introduce a color collection of ancient Egyptian painting colors for color matching of modern digital images. A total of 134 original and 168 replica/repair painting samples were selected from the digital repositories of various authoritative museum collections, focusing on painting patterns formed on object surfaces using coloring agents. The collected samples, spanning from the Ancient Kingdom of Egypt to the Greco-Roman period, encompass distinct types of ancient Egyptian paintings. The diversity and chronological distribution of these samples suggest that the color use in ancient Egyptian paintings is closely linked to the burial culture, coffin decoration, religious beliefs, and policy changes. Color analysis of the collected samples using the natural color system revealed that the predominant colors in ancient Egyptian paintings tend to be in the red and yellow spectrum, while the blue, green, and purple spectrum is relatively less prominent. This can be attributed to the historical development of colors, the scarcity of mineral resources, and the symbolic significance of colors in ancient Egyptian culture. Finally, a collection of ancient Egyptian painting colors was selected from extracted colors based on color differences to reflect the color characteristics of ancient Egyptian paintings. Furthermore, the construction method of color palettes with different thematic images and the practical application of these palettes in digital patterns using the proposed color collection were demonstrated to offer a reference for designers.

This research delves into the development of the Urban Color Plan for Ledro Valley, in Italy. Urban color, encompassing both natural and built elements, plays a crucial role in spatial perception, impacting an individual's cognitive and sensory experiences. This study aims to address the complexity of color planning by an operational method grounded in scientific research. Through the analysis of existing color plans and the study of this specific case, the paper proposes a methodology which emphasizes scientific scrutiny by encompassing factors like historical context, social aspects, environmental influences and a chromatic and material facade survey. The research outlines the multifaceted scales of intervention, ranging from urban mapping to material quality considerations. The Ledro Valley case study exemplifies the application of this methodology, revealing the challenge in harmonizing the diverse historical-political realities of this Valley. The results showcase a flexible color plan that unifies the territory while still preserving the distinct identities of individual previous municipalities, demonstrating the plan's adaptability and potential for enhancing the overall urban environment.

Digitizing motion picture films is a crucial aspect of archival practices. Nevertheless, the primary purpose of this process is to convert analog film into a digital signal suitable for recording back onto film. Thus, the most popular color film system encoding, such as Cineon or Academy Density Exchange (ADX), may present some limits for the preservation and restoration practices. In this paper, Cineon and ADX systems are summarized and analyzed, and an experimental application conducted on modern cinematographic film scanners has been made to evaluate the integration of these encoding systems into these devices. Results have been examined and discussed to underline the constraints and possibilities of these color encoding systems for archival purposes.

The performance of color matching functions (CMFs) is important to color specification and calibration. In comparison to the great number of studies focusing on the effect of primary set, few studies focused on how observer age and field of view (FOV) jointly affected the performance of CMFs. In this study, a color matching experiment with three different primary sets, which were carefully selected based on our previous study, was carried out by two observer age groups under four FOVs (i.e., 2°, 4°, 8°, and 13°). The results suggested that the observer age had a more significant effect than the FOV, and the change of the FOV did not introduce a systematic trend to the color matching results. Neither the CIE 1931 2° nor 1964 10° CMFs were found to accurately characterize the color matches. The CIE 2006 CMFs with the FOV set to the experiment setup also did not have good performance. On average, the CIE 2006 2° CMFs were found to have the best performance, without considering the effects of the observer age and FOV.