8 Colour Quantization of Colour Construct Code in CIELAB Colour Space Using K-Means Clustering and Hungarian Assignment

2015 ◽  
pp. 671-681
Author(s):  
Kam Meng Goh ◽  
Zubairy bin Ismaail
Keyword(s):  
Colour Space ◽  
Cielab Colour

scholarly journals Preferred skin reproduction centres for different skin groups

2020 ◽  
Vol 2020 (28) ◽  
pp. 109-113
Author(s):  
Rui Peng ◽  
Ming Ronnier Luo ◽  
Mingkai Cao ◽  
Yuechen Zhu ◽  
Xiaoxuan Liu ◽  
...  
Keyword(s):  
Ethnic Groups ◽  
South Asian ◽  
Skin Colour ◽  
Psychophysical Experiment ◽  
Colour Centre ◽  
Colour Space ◽  
Colour Centres ◽  
Darkened Room ◽  
Cielab Colour ◽  
Facial Images

Producing preferred skin colours is vital for the digital images on mobile phone manufacturers. Previous studies investigated the skin colours only in chromatic plane excluding lightness. A psychophysical experiment was conducted to determine preferred skin colour centres for different skin colour types on mobile displays in a darkened room. Ten facial images were selected for the experiment to cover different skin colour types (Caucasian, Oriental, South Asian and African). A set of 49 predetermined colour centres uniformly sampled within the skin colour ellipsoid in CIELAB colour space was used to morph skin colours of test images. Thirty observers from each of the 3 ethnic groups (Caucasian, Oriental and South Asian) participated in the experiment. The preferred skin colour centre and region in the form of ellipsoid for each skin group were reported. It was found that the preferred colour centres from different skin colour types were very similar except their lightness as expected, and were also quite similar between the observers from different ethnic groups.

scholarly journals Predicting the colour associated with odours using an electronic nose

2021 ◽  
Author(s):  
Ryan Ward ◽  
Shammi Rahman ◽  
Sophie Wuerger ◽  
Alan Marshall
Keyword(s):  
Electronic Nose ◽  
Human Perception ◽  
Olfactory Perception ◽  
Colour Space ◽  
Crossmodal Associations ◽  
Electronic Nose System ◽  
Cielab Colour

Predicting olfactory perception with an electronic nose can aid in the design and evaluation of olfactory-based experiences. We investigate whether the human perception of odours can be predicted outside the bounds of perceived pleasantness and semantic descriptors. We tuned an electronic nose to predict an odour's colour in the CIELAB colour space using human judgements. This revealed that the crossmodal associations people have towards colours could be predicted. Our electronic nose system can predict an odour's colour with a 70 – 81% machine-human similarity rating. These findings suggest a systematic and predictable link exists between the chemical features of odours and the colour associated to them. These findings highlight the possibilities of predicting human olfactory perception using an electronic nose.

The influence of mould fungus on pigments used in wall and ceiling décor on the example of the wooden church of Saint George in Ostropa

2020 ◽  
Vol 110 ◽  
pp. 48-53
Author(s):  
Adrianna Lipiec ◽  
Bogusław Andres
Keyword(s):  
Aspergillus Niger ◽  
Carbon Black ◽  
Prussian Blue ◽  
Colour Space ◽  
Mould Fungus ◽  
Zinc White ◽  
Cielab Colour

The influence of mould fungus on pigments used in wall and ceiling décor on the example of the wooden church of Saint George in Ostropa. This research aimed to establish the change in colour of selected pigments used in polychrome due to the effects of Aspergillus niger. The research was conducted on the following pigments: cremnitz white, zinc white, vermilion, colcothar, chrome green, artificial ultramarine, burnt umber, carbon black, smalt, minium, azurite, Prussian blue and chalk. Measurements were taken using a colorimeter in the CIELAB colour space. The biggest change in colour was exhibited by artificial ultramarine, while the most stable in colour turned out to be minium. The smallest change in colour of dried samples was shown by burnt umber, while the biggest change was noted again for artificial ultramarine.

Colour variation in standard soil-colour charts

Soil Research ◽  
2005 ◽  
Vol 43 (7) ◽  
pp. 827 ◽  
Author(s):  
M. Sánchez-Marañón ◽  
R. Huertas ◽  
M. Melgosa
Keyword(s):  
Analysis Of Variance ◽  
Colour Difference ◽  
Colour Space ◽  
Perception Threshold ◽  
Colour Variation ◽  
Standard Soil ◽  
Colour Changes ◽  
Cielab Colour

This paper presents colourimetric analyses of 6 standard soil-colour charts (1372 chips) from different manufacturers, editions, and degrees of use. The CIELAB hab, L*, and C*ab were found to have significant (analysis of variance, P < 0.05) variations among tested charts, and the Munsell hue, value, and chroma measured in most chips varied from their notation by as much as 1 unit. This discrepancy can be attributed to printing differences and/or colour fading. The Munsell loci of constant hue and chroma plotted in CIELAB colour space showed that colour fading is not uniform, so that visual steps between neighbouring chips change, and constant hue and chroma lines become deformed. The colour difference between chips identically designated in two charts ranged from 0.94 CIEDE2000 units (above perception threshold) for charts from the same manufacturer and degree of use, to 3.72 CIEDE2000 units for old charts from 2 different manufacturers. Chips from old charts became yellowish, darker, and less saturated. These colour changes are consistent with the responses of 10 observers who, on assessing 10 soil-colour samples, reported Munsell notations to have redder hue, lighter value and greater chroma. Periodic colourimetric checking of soil-colour charts would be advisable in order to avoid mistakes in soil-colour description.

Synthesis, characterization and colour determination using CIELAB colour space of stilbene dyes

2013 ◽  
Vol 10 (4) ◽  
pp. 807-816 ◽  
Author(s):  
Maria Elena Grad ◽  
Georgeta Maria Simu ◽  
Simona Gabriela Muntean ◽  
Gheorghe Ilia
Keyword(s):  
Colour Space ◽  
Cielab Colour

scholarly journals Dependence of colour difference formulae on regular changes of colour coordinates in CIELAB colour space

2019 ◽  
Vol 70 (03) ◽  
pp. 248-254
Author(s):  
UGUR ONUR CINKO ◽  
BEHCET BEHCET BECERIR
Keyword(s):  
Empirical Study ◽  
Colour Difference ◽  
Colour Space ◽  
Special Software ◽  
Best Fitting ◽  
Coordinate Changes ◽  
Cielab Colour ◽  
Colour Coordinates

Four colour difference formulae [CIELAB (1976), CMC (2:1), CIE94 (2:1:1) and CIEDE2000 (2:1:1)] were assessed in CIELAB colour space for regular changes in colour coordinates. L*, a* and b* coordinates were changed regularly both as increasing and decreasing steps in different lightness and hue regions of the colour space. The dependence and consistency of the four formulae were researched depending on regular and constant colour coordinate changes. The aim of the empirical study was to determine if there could be a possibility of using different colour difference formulae in different hue regions of CIELAB colour space; in the region of bulk that each formula would give the best fitting and the most reliable results. The empirical study was carried out by using a special software which was prepared for the purpose. The results showed that CIELAB and CIE94 gave corresponding results with each other in the computing ranges. All the formulae showed different computing characteristics in the computation ranges. CMC formula gave the highest colour differences when computing near the grey point. It was concluded that CIEDE2000 formula suited itself the best according to the changes in computing steps. A more complicated software would be necessary to determine the sensitivity of the formulae by which the computing would be performed by changing all the coordinates (L*, a* and b*) at the same time.

Transformation of NCS data into CIELAB colour space

1986 ◽  
Vol 11 (2) ◽  
pp. 146-152 ◽  
Author(s):  
Gunilla Derefeldt ◽  
Christer Sahlin
Keyword(s):  
Colour Space ◽  
Cielab Colour
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