scholarly journals A Novel Method of Color Appearance Simulation Using Achromatic Point Locus With Lightness Dependence

i-Perception ◽  
2018 ◽  
Vol 9 (2) ◽  
pp. 204166951876173 ◽  
Author(s):  
Ichiro Kuriki
Keyword(s):  
Dynamic Range ◽  
Simple Algorithm ◽  
Color Difference ◽  
Color Appearance ◽  
Proposed Model ◽  
Color Differences ◽  
Cone Response ◽  
Human Color Vision ◽  
Conventional Models ◽  
Cie Lab

The purpose of the present study is to propose a simple algorithm for color appearance simulation under a color illuminant. Achromatic point is a chromaticity of rays that appear neither red nor green, neither blue nor yellow under a given illuminant condition. Saturation and hue of surface colors are evaluated with respect to the achromatic point of the same lightness, while the achromatic point under a colored illuminant depends on the lightness tested. We previously found that this achromatic point locus can be simply approximated as a line with a parallel offset from the lightness axis of CIE LAB space normalized to daylight. We propose a model that applies shifts in the lightness direction after applying hue/saturation shifts using the cone-response (von Kries) transformation under an iso-lightness constraint, such that achromatic points would be aligned with the lightness axis in the CIE LAB space under daylight normalization. We tested this algorithm, which incorporates evaluation of color appearance in different lightness levels, using #theDress image. Resemblance between our simulation and subjective color-matching results implies that human color vision possibly processes shifts in color and lightness independently, as a previous study reported. Changes in the chromaticity distribution of the images were compared with conventional models, and the proposed model preserved relative color difference better, especially at the lower lightness levels. The better performance in lower lightness levels would be advantageous in displays with wider dynamic range in luminance. This implies that the proposed model is effective in simulating color appearance of images with nonnegligible lightness and color differences.

Influence of Fe2+ on the Color Appearance of Yellow-Green Peridot

2011 ◽  
Vol 492 ◽  
pp. 370-373 ◽  
Author(s):  
Wei Xi Tang ◽  
Ying Guo ◽  
Li Xia Ma
Keyword(s):  
Color Space ◽  
Chromatic Aberration ◽  
Color Difference ◽  
Color Appearance ◽  
Chemical Compositions ◽  
Significance Level ◽  
Icp Ms ◽  
Difference Formula ◽  
Chromaticity Coordinates ◽  
Cie Lab

Twenty-eight yellow-green color of uniform, high clarity and similar thickness of 5 mm × 7 mm oval faceted peridots from Jiaohe Jilin province were examined by LA-ICP-MS and Color i5 to test their chemical compositions and L*, C* and ho. The correlations between Fe2+ and color parameters were analyzed, in order to establish the influence on the color appearance of Fe2+. The chemical formula of the twenty-eight peridots is (Mg1.84,Fe0.19)2.04[(Si0.982,Al0.001)0.983O4], which was calculated by oxygen atom. It reveals that 0.19 mol Fe2+ is concluded in one mol peridot, and Fe2+ is the colorant of peridot. Based on the CIE 1976 L*a*b* uniform color space, relationships between chromaticity coordinates a*, b* and chromaticity C* were analyzed by Two-way ANOVA, of which the results showing that the influence of b* on C* (rb*×C*=0.996) is much more prominent than a* on C* (ra*×C*= -0.383). By partial correlation analysis of the results calculated through CIE LAB color-difference formula, it can be discovered that lightness difference DL* has a better correlation with chromatic aberration DE* than DC* and DH*, whereas the significance level ρDC*×DE* > 0.05, rDH*×DE* > 0.05, it reveals that DE* is more sensitive to DL*. At the same time, L* changes the most with the contributions of Fe2+ compared with other parameters of peridot. It is concluded that, with the help of L*, Fe2+ has a further influence on the color appearance of peridot.

Color Difference Evaluation Based on Image Color Appearance Model

2012 ◽  
Vol 200 ◽  
pp. 637-640
Author(s):  
Jing Liang ◽  
Yong Bin Zhao ◽  
Hui Gao
Keyword(s):  
Calculation Method ◽  
Color Difference ◽  
Color Images ◽  
Color Appearance ◽  
Appearance Model ◽  
Difference Formula ◽  
Difference Calculation

The iCAM (image color appearance model) as the most advanced modern color appearance model is constantly being put into use. In color images industry, the evaluation of the color difference is significant. This article will focus on color difference formula of image color appearance model and analysis its reasonable color difference calculation method, which reflects the advantages of image color appearance model.

scholarly journals UCAN: A Learning-based Model to Enhance Poorly Exposed Images

2020 ◽  
Author(s):  
Lucas R. V. Messias ◽  
Cristiano R. Steffens ◽  
Paulo L. J. Drews-Jr ◽  
Silvia S. C. Botelho
Keyword(s):  
Image Quality ◽  
Image Enhancement ◽  
Dynamic Range ◽  
Low Contrast ◽  
Qualitative And Quantitative ◽  
Fast Learning ◽  
Proposed Model ◽  
Quantitative Results ◽  
Critical Process ◽  
Poor Lighting

Image enhancement is a critical process in imagebased systems. In these systems, image quality is a crucial factor to achieve a good performance. Scenes with a dynamic range above the capability of the camera or poor lighting are challenging conditions, which usually result in low contrast images, and, with that, we can have the underexposure and/or overexposure problem. In this work, our aim is to restore illexposed images. For this purpose, we present UCAN, a small and fast learning-based model capable to restore and enhance poorly exposed images. The obtained results are evaluated using image quality indicators which show that the proposed network is able to improve images damaged by real and simulated exposure. Qualitative and quantitative results show that the proposed model outperforms the existing models for this objective.

scholarly journals A MONITORING METHOD OF COLOR DECAYING FOR COLORED PATTERNS IN ARCHITECTURAL HERITAGE

2019 ◽  
Vol XLII-2/W11 ◽  
pp. 1193-1198
Author(s):  
L. Zhang ◽  
J. Xie ◽  
L. Qin ◽  
Z. Liu ◽  
G. Liu
Keyword(s):  
Good Health ◽  
Color Difference ◽  
Health Condition ◽  
Architectural Heritage ◽  
Monitoring Method ◽  
Special Part ◽  
Color Differences ◽  
The Status ◽  
Set Up ◽  
Colored Pattern

<p><strong>Abstract.</strong> As a special part of architectural heritage, the colored pattern is not only artwork to decorate the architecture, but information reflecting specific historical era. So it has great cultural and artistic value. However, the colored pattern is one of the most sensitive types of cultural relics, which is sensitive to natural environment changes and highly vulnerable to erosion. In order to strengthen the protection of colored patterns in history architectures, it is necessary to monitor the status quo of them.</p><p>This work introduces a monitoring method of color decaying for colored patterns in architecture: set up the illuminants, adjust the illuminants, detect the color information and calculate the color difference. Based on the color difference by CIE DE2000 formula, the color decaying status of the pattern can be evaluated. The monitoring period should be at least three months.</p><p>About four years’ work has been carried out for colored patterns in the Long Corridor of the Summer Palace, and the color differences &amp;Delta;E<sub>00</sub> are about from 2 to 5, some can be over 9. In result, most colored patterns keep in good health condition. Color decaying happens every time and there are slight changes in most colored patterns. In 2nd quarter 2017, aware changes happened in nearly all the patterns. According to the color difference to evaluate the color decaying of the colored patterns, it is an efficient method to analyze the health status of colored patterns.</p>

Binocular rivalry between identical retinal stimuli with an induced color difference

2008 ◽  
Vol 25 (3) ◽  
pp. 361-364 ◽  
Author(s):  
SANG WOOK HONG ◽  
STEVEN K. SHEVELL
Keyword(s):  
Binocular Rivalry ◽  
Binocular Disparity ◽  
Color Difference ◽  
Color Appearance ◽  
Neural Representation ◽  
Stereoscopic Depth ◽  
Perceptual Alternation ◽  
Physically Identical ◽  
Open Question

An open question in color rivalry is whether alternation between two colors is caused by a difference in receptoral stimulation or a difference in the neural representation of color appearance. This question was examined with binocular rivalry between physically identical lights that differed in appearance due to chromatic induction. Perceptual alternation was measured between gratings of the same chromaticity; each one was presented within a different patterned surround that caused the gratings, one to each eye, to appear unequal in hue because of chromatic induction. The gratings were presented dichoptically with binocular disparity so the rivalrous gratings appeared in front of the surround. Perceptual alternation in hue was found for the two physically identical chromaticities. Stereoscopic depth also was perceived, corroborating binocular neural combination despite color rivalry (Treisman, 1962). The results show that color rivalry is resolved after color-appearance shifts caused by chromatic context, and that color rivalry does not require competing unequal cone excitations from the rivalrous stimuli.

A Patch Antenna Design for Giga Frequency Unmanned Aerial Vehicles Application

2021 ◽  
Vol 13 (1) ◽  
pp. 01-07
Author(s):  
Dr.M.D. Javeed Ahammed ◽  
Dr.G. Srinivasa Rao
Keyword(s):  
Patch Antenna ◽  
Return Loss ◽  
Surface Current ◽  
Vital Role ◽  
Frequency Range ◽  
Gain Bandwidth ◽  
Proposed Model ◽  
Major Parameter ◽  
Aerospace Technology ◽  
Conventional Models

In this paper a present time developing application is used that is a UAV Antenna in aerospace technology. These antennas play a vital role in this WIMAX technology. A patch antenna is designed such that all the dimensions should be shrinked yet efficient in radiation in comb shape and this proposed antenna is used at 4.2GHz frequency range. A CST tool is used for designing and simulating our antenna all the dimensions taken for proposed antenna are comparatively less when compared to conventional models. Low return loss, gain, bandwidth and VSWR are optimized by using this design the efficiency is also enhanced by 95% which makes our antenna suitable to the UAV WIMAX applications. Surface current is also one of the major parameter which is reduced by our proposed model.

scholarly journals Color agreement between try-in paste and resin cement: Effect of thickness and regions of ultra-translucent multilayered zirconia veneers

2019 ◽  
Vol 13 (1) ◽  
pp. 61-67
Author(s):  
Mehdi Daneshpooy ◽  
Fatemeh Pournaghi Azar ◽  
Parnian Alizade Oskoee ◽  
Mahmoud Bahari ◽  
Saeede Asdagh ◽  
...  
Keyword(s):  
Calculated Data ◽  
Color Difference ◽  
Resin Cement ◽  
Zirconia Ceramic ◽  
Resin Cements ◽  
Cubic Zirconia ◽  
Composite Substrate ◽  
Cie Lab ◽  
Colorimetric Evaluation

Background. The current study aimed at identifying the color agreement between try-in pastes and the respective resin cements and investigated the effect of thickness and regions of Ultra-Translucent Multilayered Zirconia Veneers. Methods. A total of 90 cubic zirconia discs were prepared at two different thicknesses (0.5 mm and 0.7 mm) (n=45) in five groups in terms of the shade of the try-in paste and resin cement as follows: Universal, Clear, Brown, White and Opaque. Try-in paste and the respective resin cement were applied between the specimens and composite substrate, respectively, and colorimetric evaluation was carried out using CIE-Lab system. For each specimen, ΔE between the try-in paste and cement was calculated. Data were analyzed with SPSS 17 using Multifactor ANOVA (P<0.05). Results. Multifactor ANOVA results showed that ΔE values were significantly affected by the resin cement shade and the thickness of ceramic veneer (P<0.05). The results showed better shade agreement between the try-in paste and the respective resin cement with thicker ceramic veneers. The results of Tukey HSD revealed that ΔE values for the Clear, Universal and Brown shades were less than those of the White and Opaque shades. Lighter shades exhibited better agreement between the try-in paste and the respective resin cement. Conclusion. Perceptible color difference was found between the try-in pastes and the respective resin cement in most colors investigated. Although, the agreement of the try-in pastes and the respective resin cement was affected by the thickness of zirconia veneers, the different regions of multilayered ultra-translucent zirconia ceramic showed no significant effect.

Subjective Sensation of Color Differences – Determination of Thresholds Depending on Color Tones and Resolution

2015 ◽  
Vol 21 (1) ◽  
pp. 21-27 ◽  
Author(s):  
Christian Brischke ◽  
Tanja Borcharding ◽  
Uta Mengel
Keyword(s):  
Color Space ◽  
Color Difference ◽  
Threshold Values ◽  
Color Tone ◽  
Color Changes ◽  
Art Objects ◽  
Color Differences ◽  
Subjective Sensation ◽  
Total Color Difference

Abstract Colors are frequently defined by three points on the L*a*b* coordinates of the CIELAB color space, and the distance between two colors can be expressed as the total color difference ΔE. In particular with respect to reproducibility of print media color differences are an important parameter, as well as for car finishes and textile dyes. Color changes are also the result of ageing and weathering which is an issue for art objects and in the building and restoration sector. However, the subjective perceptibility of color differences depends on numerous factors and general thresholds are difficult to define. This study aimed therefore on defining tolerance levels for color changes in dependence of color tones and color tone combinations as well as their resolution. In total 30 test persons evaluated samples, which had been painted with acrylic artist colors with defined color differences (ΔE = 0–7). The test subjects realized color differences already at ΔE = 1–4 for the highest resolution. Threshold values have been identified for different tones as well as the effect of interdependencies between tones and the level of color heterogeneity between adjacent areas.

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