scholarly journals About quantifying small color differences in digital images

2020 ◽  
Vol 44 (4) ◽  
pp. 606-617
Author(s):  
I.G. Palchikova ◽  
E.S. Smirnov ◽  
O.A. Barinova ◽  
I.V. Latyshov ◽  
V.A. Vasiliev ◽  
...  
Keyword(s):  
Computer Vision ◽  
Color Difference ◽  
Visible Spectral Range ◽  
Color Segmentation ◽  
Digital Cameras ◽  
Color Tone ◽  
Global Threshold ◽  
Color Differences ◽  
Otsu Method ◽  
First Time

We discuss aspects of the use and possibilities provided by three-color colorimeters or digital cameras in problems of detecting small color differences by computer vision methods. The spectral dependence of the total color differences between pairs of visually indiscernible monochromatic stimuli is experimentally revealed. An experimental setup based on the UM-2 monochromator is created for producing a digital atlas of monochromatic stimuli at 1-nm increments. The atlas serves to test the color gamut and color differentiation of cameras. It is experimentally shown that in the visible spectral range a color difference of 3 units is detected by pairs of stimuli that are unevenly distributed across the spectrum and differ in wavelengths from 1 to 6 nm. The capabilities of computer vision are tested on the examples of identifying additional texts during a technical and forensic examination of documents. A new algorithm is developed for finding and quantitatively characterizing color difference of inserts based on a digital image of the inscription. In the algorithm, the objective analysis of the image is divided into a block of color segmentation and that of color tone and color difference assessment. With such an approach, the color segmentation block performs preprocessing functions, making a border map for the classes with different colors for the subsequent calculations. The Otsu method of optimal global threshold transformation is for the first time applied to a problem of image segmentation by color saturation. The trial of the algorithm confirms its efficiency in the solution of expert tasks.

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.

scholarly journals RECEIVING AND PROPERTIES OF NEW NANO COMPOSITE CARBON MATERIALS

2018 ◽  
Vol 59 (8) ◽  
pp. 75 ◽  
Author(s):  
Ravil K. Yafarov
Keyword(s):  
Carbon Materials ◽  
Microwave Plasma ◽  
High Surface ◽  
Carbon Films ◽  
Visible Spectral Range ◽  
Nano Composite ◽  
Macro Cell ◽  
Cell Structures ◽  
First Time ◽  
Composite Carbon

The effect of self-organization of diamond nanocrystallites in graphite and in the polymer-like carbon films was discovered for the first time at deposition from vapors of ethanol of low pressure with the use of non-equilibrium high-ionized microwave plasma. The technology of receiving nanocomposite diamond-graphite covers with adjustable thresholds of field emission in the range from 5-7 to 20 V/mm and density of currents higher than 100A/cm2 was developed. The possibility of receiving of insular carbon coverings with super high surface density on crystals of silicon as well as   the quasi-closed cellular macro cell structures with transparent graphene-like "windows" in the visible spectral range was shown.

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>

Visual and Instrumental Colorimetric Assessments of Small Color Differences on Translucent Dental Porcelain

1989 ◽  
Vol 68 (12) ◽  
pp. 1760-1764 ◽  
Author(s):  
R.R. Seghi ◽  
E.R. Hewlett ◽  
J. Kim
Keyword(s):  
Material Selection ◽  
Color Difference ◽  
Human Observer ◽  
Clinical Use ◽  
Restorative Dentistry ◽  
Colorimetric System ◽  
Color Differences ◽  
Precise Relationship ◽  
The Relationship ◽  
Further Development

The CIELAB colorimetric system was used for the study of the relationship between measured color difference values and human observer responses. This study verified that a specific, visually meaningful and precise relationship exists between the magnitude and direction of the measurements and the average dental-observer responses. The results support the use of this system in dentistry as a means of evaluating color by differences. The further development of such systems for clinical use would be warranted and could serve as a valuable tool for material selection and restoration design, particularly in the area of aesthetic restorative dentistry.

Note. Visual and Instrumental Color Evaluation in Red Wines

2001 ◽  
Vol 7 (5) ◽  
pp. 439-444 ◽  
Author(s):  
J. A. Martínez ◽  
M. Melgosa ◽  
M. M. Pérez ◽  
E. Hita ◽  
A. I. Negueruela
Keyword(s):  
Color Difference ◽  
Red Wines ◽  
Preliminary Estimate ◽  
Northern Spain ◽  
Experimental Conditions ◽  
Instrumental Color ◽  
A Value ◽  
Normal Color Vision ◽  
Color Differences ◽  
Path Lengths

The color of 15 red wines from several wineries within the renowned wine-producing region Rioja (Northern Spain) was measured by spectrophotometric and spectroradiometric techniques and was visually assessed in a pair-comparison experiment by a panel of 10 experienced observers having normal color vision. Correlation between instrumental color measurements made by spectrophotometric and spectroradiometric techniques was very low, as expected from major differences in the experimental conditions employed (different illumination, path lengths and glass effects). Spectroradiometric measurements at the center of the wine sampler and at positions displaced 1 cm in the horizontal and vertical directions were quite different, mainly because of an increase of the lightness L*, the average color differences between them being high (3.5 and 2.6 CIELAB units, respectively). A 50% acceptance percentage resulted for a color difference of 2.8 CIELAB units, using a reference anchor-pair of wine samples with 4.0 CIELAB units. Thus, a value around 3.0 CIELAB units should be considered a preliminary estimate of the acceptable tolerance by the human eye for red wines poured in standard wine samplers.

Color difference formulae evaluation by method of adjustment

2014 ◽  
Vol 11 (1) ◽  
pp. 89-94 ◽  
Author(s):  
A. Abbasi ◽  
M. Vik ◽  
M. Vikova
Keyword(s):  
Color Difference ◽  
Psychophysical Method ◽  
Psychophysical Experiment ◽  
Statistical Measures ◽  
Color Differences ◽  
The Mean ◽  
Different Color ◽  
Method Of Adjustment ◽  
Visual Results ◽  
Test Color

This experiment was carried out to test color difference formulae by method of adjustment. 6 different color centers (Red, Yellow, Green, Blue-Green, Blue and Violet) were chosen for this psychophysical experiment. 336 virtual sample pairs were prepared. The mean color difference was three CIELAB units. Each pair was assessed by a panel of 15 observers using psychophysical methods called Method of Adjustment. These visual data were used to test color-difference formulae: CIELAB, CMC, CIE94, DIN99d and CIE2000 with the help of simple statistical measures i.e., PF/3 and Stress. It was found that the visual results obtained from psychophysical method of adjustment show that CIE94 as well as DIN99d still perform well for small color differences.

Assessment of Appearance Match by Visual Observation and Clinical Colorimetry

1989 ◽  
Vol 68 (5) ◽  
pp. 819-822 ◽  
Author(s):  
W.M. Johnston ◽  
E.C. Kao
Keyword(s):  
Rating Scale ◽  
United States Public Health ◽  
Color Difference ◽  
The United States ◽  
Order System ◽  
Visual Rating ◽  
Color Differences ◽  
Appearance Matching ◽  
Visual Rating Scale ◽  
Cielab Color

Judgments of appearance matching by means of the visual criteria established by the United States Public Health Service (USPHS) and by means of an extended visual rating scale were determined for composite resin veneer restorations and their comparison teeth. Using a colorimeter of 45°/0° geometry and the CIELAB color order system, we used the color of the restorations and comparison teeth to calculate a color difference for every visual rating. Statistically significant relationships were found between each of the two visual rating systems and the color differences. The average CIELAB color difference of those ratings judged a match by the USPHS criteria was found to be 3. 7. However, the overlap in ranges of the color differences for those comparisons rated matches and mismatches indicates the importance of other factors in appearance matching, such as translucency and the effects of other surrounding visual stimuli. The extended visual rating scale offers no advantages to the more broadly defined criteria established by the USPHS.

Sign in / Sign up

Export Citation Format

Share Document