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.

Color changes of ash wood (Fraxinus excelsior L.) caused by thermal modification in air and steam

2021 ◽  
Vol 116 ◽  
pp. 21-27
Author(s):  
Jakub Gawron ◽  
Monika Marchwicka
Keyword(s):  
Color Space ◽  
Color Difference ◽  
Thermal Modification ◽  
Fraxinus Excelsior ◽  
Space Model ◽  
Color Changes ◽  
Cielab Color Space ◽  
Before And After ◽  
Total Color Difference ◽  
Cielab Color

Color changes of ash wood (Fraxinus excelsior L.) caused by thermal modification in air and steam. Ash wood samples of 20x20x30 mm were subjected to thermal modification in different conditions. The thermal modification was conducted in air at 190 °C and in steam at 160 °C. For both environments modification lasted 2, 6 and 10 hours. Samples color parameters were measured before and after thermal modification on the basis of the mathematical CIELab color space model. Changes in all parameters (L, a and b) were observed, the highest in lightness (L) - darker color. The total color difference (ΔE) and chromaticity change (ΔC) were calculated for all samples. The highest value of ΔE was obtained for wood modified in the air at 190 °C for 10 h. The highest value of ΔC was obtained for wood modified in steam at 160 °C for 10 h. However, the value obtained for wood modified in the air at 190 °C for 10 h were only slightly lower.

scholarly journals Drying of Steaming Maple Timber in Drying Kilns, While Preserving the Color Acquired by the Wood Steaming Process

2020 ◽  
Vol 328 ◽  
pp. 04004
Author(s):  
Ladislav Dzurenda
Keyword(s):  
Color Space ◽  
Free Water ◽  
Color Difference ◽  
Thermal Processes ◽  
Drying Process ◽  
Negative Aspect ◽  
Drying Time ◽  
Color Changes ◽  
The Difference ◽  
Total Color Difference

The paper presents a mode for drying steaming maple timber of thickness h = 38 mm from moisture W1 = 50 % to W2 = 10 %, while preserving the color of wood obtained by the steaming process. The drying process is divided into two parts. Evaporation of free water from wet wood at drying medium temperatures td = 35 - 40 °C and evaporation of water from wood below the hygroscopicity limit W ≤ 25 % at drying medium temperatures td = 70 - 80 °C. Total color difference ΔE* determined by the difference in values on the CIE L*a*b* color space coordinates dried by the proposed mode for steaming maple timber and the reference values ΔE* = 1.03. According to the categorization of wood color changes in thermal processes by work (Cividini et al. (2007), this change belongs to the category of small color changes. A negative aspect of this drying mode is the approx. 25 % increase in timber drying time.

Evaluation of Microwave and Ozone Disinfections on the Color Characteristics of Iranian Export Raisins Through an Image Processing Technique

2019 ◽  
Vol 82 (12) ◽  
pp. 2080-2087
Author(s):  
REZA SADEGHI ◽  
ESMAEEL SEYEDABADI ◽  
RAHIL MIRABI MOGHADDAM
Keyword(s):  
Image Processing ◽  
Color Difference ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Storage Pests ◽  
Color Changes ◽  
Color Characteristics ◽  
Hue Angle ◽  
Total Color Difference ◽  
Ozone Treatments

ABSTRACT Raisins are one of the most important Iranian export products but are threatened by various storage pests. Because of the disadvantages of fumigants, we evaluated alternative microwave and ozone methods for their disinfection and the side effects on raisin qualities. To perform microwave disinfection, the studied raisin samples were exposed to microwave powers of 450, 720, and 900 W for 20, 30, 40, and 50 s. Also, ozone treatments included various combinations of ozone concentrations (2, 3, and 5 ppm) and exposure times (15, 30, 45, 60, and 90 min). An image processing technique was implemented to determine the color changes of raisins in terms of lightness, redness, yellowness, total color difference, chroma, and hue angle. The results revealed that increasing the microwave power and exposure time might lead to further changes of the previously mentioned color characteristics. Compared with the microwave treatments, ozone treatments had fewer effects on those features. Generally, microwave and ozone methods could successfully disinfect Oryzaephilus surinamensis in raisins, with acceptable changes in all the color characteristics. Hence, the previously mentioned methods are proposed as alternative chemical fumigants. HIGHLIGHTS

scholarly journals The Efficacy of Linked Color Imaging in the Endoscopic Diagnosis of Barrett’s Esophagus and Esophageal Adenocarcinoma

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Mamoru Tokunaga ◽  
Tomoaki Matsumura ◽  
Kentaro Ishikawa ◽  
Tatsuya Kaneko ◽  
Hirotaka Oura ◽  
...  
Keyword(s):  
Barrett’S Esophagus ◽  
Esophageal Adenocarcinoma ◽  
Barrett's Esophagus ◽  
Color Space ◽  
Color Difference ◽  
Blue Laser ◽  
Color Imaging ◽  
Color Differences ◽  
Blue Laser Imaging ◽  
Linked Color Imaging

Background. The present study aimed to evaluate the efficacy of linked color imaging (LCI) in diagnosing Barrett’s esophagus (BE) and esophageal adenocarcinoma (EAC). Methods. A total of 112 and 12 consecutive patients with BE and EAC were analyzed. The visibility scores of BE and EAC ranging from 4 (excellent visibility) to 0 (not detectable) were evaluated by three trainees and three experts using white light imaging (WLI), LCI mode, and blue laser imaging bright (BLI-b) mode. In addition, L ∗ a ∗ b ∗ color values and color differences ( Δ E ∗ ) were evaluated using the CIELAB color space system. Results. The visibility score of the BE in LCI mode ( 2.94 ± 1.32 ) was significantly higher than those in WLI ( 2.46 ± 1.48 ) and BLI-b mode ( 2.35 ± 1.46 ) ( p < 0.01 ). The color difference ( Δ E ∗ ) from the adjacent gastric mucosa in LCI mode ( 17.11 ± 8.53 ) was significantly higher than those in other modes ( 12.52 ± 9.37 in WLI and 11.96 ± 6.59 in BLI-b mode, p < 0.01 ). The visibility scores of EAC in LCI mode ( 2.56 ± 1.47 ) and BLI-b mode ( 2.51 ± 1.28 ) were significantly higher than that in WLI ( 1.64 ± 1.46 ) ( p < 0.01 ). The color difference ( Δ E ∗ ) from the adjacent normal Barrett’s mucosa in LCI mode ( 19.96 ± 7.97 ) was significantly higher than that in WLI ( 12.95 ± 11.86 ) ( p = 0.03 ). Conclusion. The present findings suggest that LCI increases the visibility of BE and EAC and contributes to the improvement of the detection of these lesions.

scholarly journals Assessment of changes in color and color parameters of light-cured composite resin after alternative polymerization methods

2013 ◽  
Vol 07 (01) ◽  
pp. 110-116 ◽  
Author(s):  
Emine Sirin Karaarslan ◽  
Bulbul Mehmet ◽  
Ertas Ertan ◽  
Mehmet Ata Cebe ◽  
Aslihan Usumez
Keyword(s):  
Composite Resin ◽  
Color Change ◽  
Color Difference ◽  
Study Groups ◽  
Color Parameters ◽  
Color Changes ◽  
Yellow Color ◽  
Before And After ◽  
Total Color Change

ABSTRACTObjective:To examine the amount of change in color and color parameters of a composite resin (Filtek P60) polymerized by five different polymerization methods.Methods: A Teflon mold (6mm in diameter, 2mm in height) was used to prepare the composite resin discs (n=10). G1: Polymerization with inlay oven; G2: Polymerization with HQTH and autoclave; G3: Polymerization with LED and autoclave; G4: Polymerization with HQTH; G5: Polymerization with LED. Colorimetric values of the specimens before and after polymerization were measured using a spectrophotometer. The CIE L*a*b color system was used for the determination of color difference. Analysis of variance (ANOVA) was used to analyze the data for significant differences. Tukey’s HSD test and paired two-tailed tests were used to perform multiple comparisons (α=.05).Results: There were no significant differences in total color change (ΔE*ab) among the polymerization groups (P>.05). However, the lowest color change (ΔE*ab) value was 3.3 in LED and autoclave; the highest color change (ΔE*ab) value was 4.6 in HQTH. For all groups, CIE L*, C*ab and a*values decreased after polymerization (P<.05). The highest Δb* and ΔC*ab values were observed in specimens polymerized in an inlay oven (P<.05).Conclusion: Composite resin material showed color changes above the clinically accepted value in all study groups (ΔE*ab≥3.3). All specimens became darker during investigation (ΔL*< 0). Specimens polymerized with inlay oven presented the highest Δb* values which means less yellow color in specimens. (Eur J Dent 2013;7:110-116)

The Contribution of Co2+ to Blue Color of Synthetic Spinel

2011 ◽  
Vol 492 ◽  
pp. 400-403
Author(s):  
Ye Ma ◽  
Ying Guo
Keyword(s):  
Color Space ◽  
Measurement Instrument ◽  
Color Difference ◽  
Color Appearance ◽  
Color Measurement ◽  
Chemical Compositions ◽  
Blue Color ◽  
Color Changes ◽  
Specimen Processing ◽  
Relationship Of

Through to 110 pieces purity transparent and color uniform, 3 x 5 x 7mm blue synthetic spinel made with the flame fusion method on chemical compositions and color parameter measurement the Co2+ content and color changes, clear the influence on Co2+ relationship of blue synthetic spinels’ color appearance. Through LA-ICP-MS to analysis the cause of colorant content, proof that with Co2+, the increase of the content of synthetic spinel will shift blue to purple tone, and C* shows a parabola form with the drop of L*, 700 ppm ~ 900 ppm place in peak. DL* Î (3.55 ~ 76.94) with Co2+ Î (4.59 ppm ~ 1849 ppm) change the largest amount, DC* Î (-9.99 ~ 29.32) next, DH* Î (-20.34 ~ 4.67) compared with before two changes smallest. Co2+ content in 100ppm below, blue color of synthetic spinel with Co2+ content increased changes greatly; 500 ~ 1500 ppm, visually achieve optimal color (C* higher); above 1500ppm, because of the Co2+ overmuch make the color burn cause the overall decline of transparency, the change of L* tends to be gentle, C* decrease obviously. Use Color i5 in standard color measurement instrument lighting source D65, measured the lightness L*, specimen Color a* and b*, chroma C* and tonal angle ho, based on the uniform color space CIE 1976 L*a*b*, in lightness minimum L 9-10 specimen (processing data for standard to 9th), with the help of DE2000 benchmark for calculating formulas, the Color, the color difference train E* by partial correlation analysis card clearly degrees of off color changes L* has certain influence on rDL*×DE*= 0.996, while rDC*×DE*= -0.427, rDH*×DE*= -0.339. Conclusion, the bule color of synthetic spinel because of its Co2+ content changes main influencing L* to contribute to its color appearance.

scholarly journals Visible color changes estimation in colorimetric determination of chromium (VI) using polymeric sensors

ACTA IMEKO ◽  
2016 ◽  
Vol 5 (3) ◽  
pp. 95 ◽  
Author(s):  
Nataliya A. Gavrilenko ◽  
Sergey V. Muravyov ◽  
Nadezhda V. Saranchina ◽  
Alexey V. Sukhanov
Keyword(s):  
Solid Phase ◽  
Tap Water ◽  
Color Difference ◽  
Colorimetric Determination ◽  
Color Analysis ◽  
Color Coordinates ◽  
Color Changes ◽  
Relative Standard ◽  
Solid Phase Spectrophotometry

<p class="Abstract"><span lang="EN-US">The paper describes an application of a kind of optical analytical method, digital color analysis (DCA), using colorimetric polymethacrylate sensors (optodes) in order to determine Cr (VI). The optodes are made of optically transparent polymethacrylate matrix (PMM) with 1.5-diphenylcarbazide immobilized. The developed optode can be used in determination of the analytes using solid phase spectrophotometry and calculating color coordinates as functions of absorbance spectra. Also color coordinates can be represented as basic color (e.g. RGB) data after the optode image digitizing. Then one can determine the content of an analyte in a sample by an appropriate color difference calculated for these coordinates. Experimental results of Cr (VI) determination in tap water show that the DCA relative standard deviation is 8-17 % and recovery is &lt; 12 % at the range of determined concentrations 0.05-1.0 </span><span lang="EN-US">mg·L<sup>–1</sup></span><span lang="EN-US">. The characteristics are comparable with those of the solid phase spectrophotometry.</span></p>

scholarly journals Texture and Color Enhancement Imaging Increases Color Changes and Improves Visibility for Squamous Cell Carcinoma Suspicious Lesions in the Pharynx and Esophagus

Diagnostics ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1971
Author(s):  
Akira Dobashi ◽  
Shingo Ono ◽  
Hiroto Furuhashi ◽  
Toshiki Futakuchi ◽  
Naoto Tamai ◽  
...  
Keyword(s):  
Squamous Cell Carcinoma ◽  
Cell Carcinoma ◽  
Squamous Cell ◽  
Narrow Band Imaging ◽  
Color Space ◽  
Color Changes ◽  
Color Differences ◽  
Color Enhancement ◽  
White Light Imaging ◽  
Suspicious Lesions

Texture and color enhancement imaging (TXI) has been developed as an image-enhanced endoscopy technology. TXI mode2 enhances texture and brightness, and TXI mode1 also enhances color. This study aims to assess the color differences in squamous cell carcinoma (SCC) suspicious lesions in the pharynx and esophagus using white light imaging (WLI), TXI mode1, TXI mode2, and narrow-band imaging (NBI). A total of 59 SCC suspicious lesions from 30 patients were analyzed. The color differences (ΔE) between the lesion and the surrounding mucosa were calculated for each modality. The color value was assessed using the Commission Internationale d’Eclairage L*a*b* color space. The visibility of the lesion in each modality was evaluated and compared to that in the WLI by six endoscopists. The mean ΔE values in the WLI, TXI mode1, TXI mode2, and NBI were 11.6; 18.6; 14.3; and 17.2, respectively, and the ΔE values of TXI mode1, TXI mode2, and NBI were significantly higher than those of the WLI (p < 0.001). No lesions had worse visibility, and 62.5% (37/59) had improved visibility, as assessed by more than half of the endoscopists in TXI mode1. TXI mode1 can enhance color changes and improve the visibility of SCC suspicious lesions in the pharynx and esophagus, compared to WLI.

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.

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