Variation of Perceived Colour Difference Under Different Surround Luminance

2020 ◽  
pp. 56-60
Author(s):  
Thilan Costa ◽  
Vincent Gaudet ◽  
Edward R. Vrscay ◽  
Zhou Wang
Keyword(s):  
Colour Difference

scholarly journals Impact of Incorporating NIR Reflective Pigments in Finishing Coatings of ETICS

2021 ◽  
Vol 6 (6) ◽  
pp. 79
Author(s):  
Nuno M. M. Ramos ◽  
Joana Maia ◽  
Andrea R. Souza ◽  
Ricardo M. S. F. Almeida ◽  
Luís Silva
Keyword(s):  
Surface Layer ◽  
Surface Temperature ◽  
Near Infrared ◽  
Building Performance ◽  
Colour Difference ◽  
Colour Perception ◽  
Composite Systems ◽  
Solar Reflectance ◽  
Building Cooling ◽  
The Impact

Near-infrared (NIR) reflective materials are being developed for mitigating building cooling needs. Their use contributes to broadening the range of colours, responding to the urban aesthetic demand without compromising the building performance. Despite the increase in NIR reflective pigments investigation, there is still a knowledge gap in their applicability, impact, and durability in multilayer finishing coatings of External Thermal Insulation Composite Systems (ETICS). Hence, the main goal of this work consists of evaluating the impact of incorporating NIR reflective pigments (NRP) in the solar reflectance of the surface layer of ETICS, without affecting the colour perception, as well as their influence on the colour durability and surface temperature. As such, colour, solar reflectance, and surface temperature were monitored for 2 years in dark-coloured specimens of ETICS, with and without NRP and a primer layer. It was confirmed that the main contribution of NRP is the increase of solar reflectance and, consequently, the decrease in surface temperature, especially for high exterior temperatures (around 30 ºC). Moreover, these pigments highly increase the NIR reflectance without affecting the visible colour. In addition, they contribute to maintaining the colour characteristics. The application of primer increased the surface temperature, especially for higher exterior temperatures. However, it contributes to a lower colour difference and solar reflectance variation, which is an important achievement for durability purposes.

Colour difference analysis of lightfastness for some direct dyes

1985 ◽  
Vol 6 (2) ◽  
pp. 85-95 ◽  
Author(s):  
Moustafa Ibrahim ◽  
S. Shakra
Keyword(s):  
Direct Dyes ◽  
Colour Difference ◽  
Difference Analysis

Assessment of bruise age on dark-skinned individuals using tristimulus colorimetry

2011 ◽  
Vol 52 (1) ◽  
pp. 6-11 ◽  
Author(s):  
D Thavarajah ◽  
P Vanezis ◽  
D Perrett
Keyword(s):  
Objective Assessment ◽  
B Value ◽  
Forensic Analysis ◽  
Control Area ◽  
Sri Lankan ◽  
Colour Difference ◽  
Tristimulus Colorimetry ◽  
South Indian ◽  
Colour Measurements ◽  
Significant Difference

Introduction Studies on the ageing of bruises have been reported on Caucasians or individuals of fair ethnicity. This study focuses on bruise changes in dark-skinned individuals using tristimulus colorimetry for forensic analysis in such individuals. Methods Eighteen subjects of South Indian or Sri-Lankan ethnicity were recruited. Subjects were bruised using a vacuum pump and then daily colour measurements were taken of the bruise using a tristimulus colorimeter. The L* a* b* readings were recorded of a control area and of the bruise until it disappeared. Two Caucasians were used for comparison. Results This study showed that, using colorimetry, bruises on dark-skinned individuals can be measured and analysed even if the bruises are unclear visually. As the bruise is beneath the skin, the colour difference Δ L*, Δ a* and Δ b* were calculated. All values showed a trend, indicating that the L* a* b* measuring technique is a reliable method to analyse bruises on dark-skinned individuals. Comparisons of Asian subjects and Caucasian subjects were performed. The largest difference was seen in the b* value. Statistical analysis showed that Δ L* colour difference was the most consistent (95% CI −4.05 to −2.49) showing a significant difference between days 1–4 and 5–8. Conclusion Objective assessment of bruises on dark-skinned individuals using the L* a* b* method of measuring gave reproducible results. Furthermore, the study showed that the yellowing of a bruise cannot be seen or measured with a tristimulus colorimeter on dark-skinned individuals due to the pigmentation of the skin. With further studies and more subjects, the age of bruises could potentially be assessed for use in forensic analysis.

Colour stability of surface finishes on thermally modified beech wood

2021 ◽  
Vol 114 ◽  
pp. 116-124
Author(s):  
Gabriela Slabejová ◽  
MÁRIA ŠMIDRIAKOVÁ
Keyword(s):  
Surface Finish ◽  
Beech Wood ◽  
Surface Finishing ◽  
Colour Stability ◽  
Colour Difference ◽  
Surface Finishes ◽  
Before And After ◽  
Thermally Modified Wood ◽  
Wood Surfaces ◽  
Modified Wood

Colour stability of surface finishes on thermally modified beech wood. The paper deals with the influence of the type of transparent surface finish on the change of colour of the surfaces of native beech wood and thermally modified wood. At the same time, the colour stability of three surface finishes on the surfaces of native and thermally modified beech wood was monitored. Beech wood was thermally modified at temperature of 125 °C for 6 hours. The thermal treatment was performed in a pressure autoclave APDZ 240, by the company Sundermann s.r.o in Banská Štiavnica. Three various types of surface finishes (synthetic, wax-oil, water-based) were applied onto the wood surfaces. The colour of the surfaces of native wood and thermally modified wood was measured in the system CIELab before and after surface finishing; the coordinates L*, a*, b*, C*ab and h*ab were measured. From the coordinates measured before and after surface finishing, the differences were calculated and then the colour difference ∆E* was calculated. Subsequently, the test specimens with the surface finishes were exposed to natural sunlight, behind glass in the interior for 60 days. The surface colour was measured at specified time of the exposure (10, 20, 30, 60 days). The results showed that the colour of the wood surfaces changed after application of the individual surface finishes; and the colour difference reached a change visible with a medium quality filter up to a high colour difference. The wax-oil surface finish caused a high colour difference on native wood and on thermally modified wood as well. On native beech wood, the lowest colour difference after exposure to sunlight was noticeable on the synthetic surface finish. On the surface of wood thermally modified, after exposure to sunlight, the lowest colour difference was noticeable on the surface with no surface finish.

Estimation of Sand Distribution in Coral Reef Environment using Colour Segmentation and Colour Thresholding Methods

2019 ◽  
Vol 1 (3) ◽  
pp. 96-104
Author(s):  
Pauleen Ong ◽  
Muhammad Suzuri Hitam ◽  
Zainuddin Bachok ◽  
Mohd Safuan Che Din
Keyword(s):  
Coral Reef ◽  
Extraction Methods ◽  
Colour Difference ◽  
Reef Environment ◽  
Still Images ◽  
Point Count ◽  
Automatic Computer ◽  
Computer Based ◽  
Coral Reef Environment ◽  
Colour Segmentation

At present, marine scientists employ manual method to estimate the components in coral reef environment, where Coral Point Count with Excel extensions (CPCe) software is used to determine the coral reef components and substrate coverage. This manual process is laborious and time consuming, and needs experts to conduct the survey. In this paper, a prototype for estimating the distribution of sand cover in coral reef environment from still images by using colour extraction methods was introduced. The colour segmentation called delta E was used to calculate the colour difference between two colour samples. Another method used was colour threshold by setting the range of sand colour pixels. The system was developed by using a MATLAB software with image processing toolbox. The developed system was semi-automatic computer-based system that can be used by researchers even with little knowledge and experience to estimate the percentage of sand coverage in coral reef still images.

Testing Colour Appearance Model Based UCS Using HDR, WCG and COMBVD Datasets

2021 ◽  
Vol 2021 (29) ◽  
pp. 381-386
Author(s):  
Xu Qiang ◽  
Muhammad Safdar ◽  
Ming Ronnier Luo
Keyword(s):  
Correlation Coefficient ◽  
Power Factor ◽  
Marked Improvement ◽  
Appearance Model ◽  
Colour Difference ◽  
Similar Performance ◽  
Model Based ◽  
Test Models ◽  
Appearance Models ◽  
Colour Appearance

Two colour appearance models based UCSs, CAM16-UCS and ZCAM-QMh, were tested using HDR, WCG and COMBVD datasets. As a comparison, two widely used UCSs, CIELAB and ICTCP, were tested. Metrics of the STRESS and correlation coefficient between predicted colour differences and visual differences, together with local and global uniformity based on their chromatic discrimination ellipses, were applied to test models' performance. The two UCSs give similar performance. The luminance parametric factor kL, and power factor γ, were introduced to optimize colour-difference models. Factors kL and γ of 0.75 and 0.5, gave marked improvement to predict the HDR dataset. Factor kL of 0.3 gave significant improvement in the test of WCG dataset. In the test of COMBVD dataset, optimization provide very limited improvement.

scholarly journals Research on double-faced jacquard fabric with compound full-backed structure of three wefts

2021 ◽  
Vol 72 (05) ◽  
pp. 491-502
Author(s):  
LINLIN BAI ◽  
JIU ZHOU
Keyword(s):  
Design Method ◽  
Single Layer ◽  
Colour Difference ◽  
Compound Structure ◽  
Critical Position ◽  
Shading Effect ◽  
Transition Effect ◽  
Structure Database ◽  
Step Number ◽  
Colour Effect

Weft-backed structures with compound weft colours can express the mixed colour effect. However, this structure is not suitable for jacquard fabrics with a double-faced shading effect in the traditional single layer design mode. Taking twenty-thread sateen with a step number (S) of 7 as an example, this paper investigates a design method for compound full-backed structure with three shaded-weave databases (SWDs) by selecting the primary weaves (PWs), designing the compound full-backed technical points and establishing the compound structure database with three SWDs. With this design method, a double-faced shading effect in combination with non-backed and full-backed effects on different sides of the jacquard fabric at the same position is generated. The fabric colour card was produced with three SWDs and three sets of different coloured wefts, and their colour values were measured, followed by an analysis of the compound structures on the reverse side, lightness, colour purity and colour difference (DE*ab) of the specimens. The results showed that the three covering effects on the reverse side, partly covered, critical position and totally covered, could be adjusted by controlling the step number and the transition direction of PW-C. For the specimens on the edges of the fabric colour card, their lightness and colour purity values showed a uniform transition effect along with the shading process; their colour differences ranged from 1.23 to 3.69, both in the range of 2–5, and showed a trace or slight colour difference between two adjacent fabric specimens, indicating that the colour shading effect with the three SWDs is stable.

scholarly journals Vector-based modelling of colour difference: a pilot study of the DE2000 colour difference model

2016 ◽  
Vol 133 (1) ◽  
pp. 15-25
Author(s):  
David P. Oulton ◽  
Stephen Westland
Keyword(s):  
Pilot Study ◽  
Colour Difference ◽  
Difference Model
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