The effects of coloured base fabric on electrochromic textile

The colour of electrochromic fabric, and its colour transitions, was explored on the basis of variations in underlying fabric colour. A complete understanding of this phenomenon is essential for the fabric’s use in full‐colour wearable displays or other applications. Previous work in this area utilised only white‐coloured starting materials. Herein, a large colour swathe of fabrics was chosen. They were loaded with the commercially available conducting polymer, PEDOT‐PSS, and were coated with an electrochromic polymer. These all‐organic substrates were then switched between their two coloured states via reversible oxidation and reduction. At every stage, coordinates in the CIE Lu′v′ colour space were measured. It was found that darker colours decrease the overall contrast of the electrochromic, with black being entirely unobservable. More vibrant colours affected the observed colour through a subtractive mixing effect, as expected, but no adverse contrast effects between the two states of the electrochromic system was observed.     

Discrimination of colours presented against different coloured backgrounds

Colour electronic displays are being used increasingly for information presentation in a wide range of applications. A prerequisite to the effective use of colour coding is that the colours be discriminable under all of the conditions in which the display will be used. For applications such as radar, medical imaging, or electronic charts, different coloured areas may be juxtaposed and coloured symbols superimposed on a multicoloured background. Under such conditions, the colours in the display may affect the appearance and discriminability of each other. the present article examines the extent to which a set of colours that is clearly distinguishable when presented against a uniform background might be confused when the members are presented against differently coloured backgrounds. This was achieved by measuring the range of chromaticities, presented against a grey background, that would be confused with each of the test colours when they were presented against different chromatic surrounds. the findings were used to derive the characteristics of sets of colours that should be discriminable in a complex display.     

Recolouring digital textile printing design with high fidelity

An algorithm of recolouring of polychromatic digital textile printing images is proposed based on the investigation of texture and colour distribution in different channels and image segmentation. A polychromatic image is first separated into monochromatic regions based on watershed transformation in CIELAB colour space. The initial markers are selected by hierarchical histogram analysis to eliminate the inherent drawbacks of over-segmentation in the watershed algorithm. Then the individual monochromatic regions can be mapped with different colours to obtain desirable designs. The artefacts in the boundaries of different regions are reduced by a technique of colour mixing through Gaussian blurring. The experimental simulation results indicated that the performance of the algorithm was quite good in both texture and colour fidelity.     

Quantifying colour appearance. part V. simultaneous contrast

Experiments were carried out to investigate the effect of simultaneous contrast on colour appearance by varying the lightness, colourfulness, and hue of an induction field surrounding a test colour. A total of 814 test/surround combinations were displayed on high-resolution colour displays. Each was assessed by a panel of five to six observers using a magnitude estimation technique. the results indicate that colours presented on a computer display are affected by simultaneous contrast in a similar way to surface colours. All three colour appearance parameters studied (i.e., lightness, colourfulness, and hue) are affected and these effects are summarized. In general, the results support and add to the findings of the other studies. the Hunt colour appearance model was tested and gave a somewhat poor prediction to this data set. Further modifications are required to improve its performance. © 1995 John Wiley & Sons, Inc.     

Optimal yarn colour combination for full‐colour fabric design and mixed‐colour chromaticity coordinates based on CIE chromaticity diagram analysis

It is challenging for textile designers to achieve full‐colour effects in woven fabric using a limited set of coloured yarns. The common problems encountered during full‐colour fabric design include an insufficient number of colours and a failure to match the fabric colour with the desired colour. Using the theories of primary colours and optical colour mixing, we examine the mixed‐colour distribution of primary colour yarns on the basis of the CIE 1976 chromaticity diagram (CIE u′v′). In our experiment, dope‐dyed polyester filament yarns were selected as raw materials. Eight kinds of gradually varied weave structures and four types of primary colour combination were adopted in order to make different types of full‐colour fabric colour chart. Spectrophotometer and DigiEye colour measurement systems were selected to measure the reflectance and colour value of the fabric samples. By comparing the colour distribution of mixed fabrics in the CIE u′v′ diagram, the relationship between the primary colour combinations and the colour distribution of mixed fabrics is discussed. Of RGB, CMY, NCS, and RGBCMY combinations, only RGBCMY resulted in a relatively complete and large colour gamut. Moreover, the colour positions of mixed fabrics in the CIE u′v′ diagram were almost all distributed on or near the connecting line of the primary colour coordinates. The specific colour position of mixed fabrics in the CIE u′v′ diagram were mainly determined by the proportion of primary colours on the fabric surface. In this way, a new method for computing colour position in the CIE u′v′ diagram is introduced.     

Lightness and hue contrast effects in surface (fabric) colours

Simultaneous contrast effects on lightness and hue in surface colours were investigated. Test colours, surrounded by induction colours, were matched by colours surrounded by neutral gray. The matching colours were selected from a series of samples that varied in either lightness or hue respectively. The lightness experiments were carried out by a panel of 20 observers on 135 test/induction colour combinations. The hue experiments were conducted on 51 test/induction colour combinations by a panel of eight observers. The lightness of the test colour was found to decrease linearly with the lightness of the induction colour, regardless of the hue of the induction colour. The magnitude of the lightness contrast effect in fabric colours was found to be about one‐quarter of that found in CRT display colours in a previous study. The hue contrast effect found in this study followed the opponent‐colour theory. Two distinctly different regions could be identified when the hue difference was plotted against hue‐angle difference between the induction colour and the test colour. The slope of the line in the region where the hue of the induction colour is close to the test colour was much larger than the slope in the other region, indicating that the hue contrast effect was more obvious when the induction colour was close to the test colour. © 2006 Wiley Periodicals, Inc. Col Res Appl, 32, 55–64, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20285     

Colour matching for smart and sustainable spinning of coloured textiles

The colours and patterns of coloured textiles are usually obtained via dyeing or printing processes. However, these processes consume large amounts of electricity and cause water pollution, which affects the ecological environment. The hand feel of dyed fabrics is superior to that of printed fabrics. Three‐channel rotor spinning is a highly flexible, adaptable and sustainable method for producing coloured textiles by blending precoloured fibres during the spinning process. Additionally, the process requires approximately half the water required for fabric dyeing or printing. Herein, the colour characteristics, as well as the advantages, of the coloured textiles produced by the new method are demonstrated. Three types of Stearns‐Noechel models are modified to describe the relationship between the blending ratios and resulting textile colours. The colour‐matching accuracy is high. As demonstrated by the results, the three‐channel rotor spinning method can effectively promote coloured textile engineering.     

Colour appearance of room colours

Psychophysical experiments were conducted to investigate the colour appearance changes between small colour patches and real room colours. The results clearly showed that colours appear lighter and more colourful for room colours. A method based on CIECAM02 was developed to quantify the colour size effect. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2010     

Michel‐Eugène Chevreul: From laws and principles to the production of colour plates

Michel‐Eugène Chevreul (1786–1889) did major scientific work in the fields of chemistry and colour and pioneered the study of simultaneous contrast. His book De la loi du contraste simultané des couleurs (The Principles of Harmony and Contrast of Colours) was published in 1839. Here, his studies pertained to simultaneous contrast, when two or more colours seen contiguously are influenced in brightness and/or in hue, and on successive contrast, when afterimages modify colour perception. He also investigated the mixed contrast that appeared in tapestries in which a mixture of colours was obtained by the plying of yarn or by hatching. Later, he reported on the influence exerted on vision by coloured objects in circular motion around an axis perpendicular to their plane (1879). Many examples and numerous experimental checks documented in his books supported his demonstration of contrast. Of particular interest are the colour plates attached to the books. Another significant work by Chevreul was a three‐dimensional colour classification system (1864), after which he manufactured a colour atlas showing colour circles and monochrome lightness scales. Data are presented from recent measurements of Chevreul's atlas circles and plates, and there is a discussion of his choice of complementary colours. © 2002 John Wiley & Sons, Inc. Col Res Appl, 27, 4–14, 2002     

Evaluation of the crispening effect using CRT‐displayed colour samples

In this study, the crispening effect was clearly observed when 38 neutral‐coloured sample pairs with only lightness differences were assessed under 5 neutral backgrounds of different lightness values. The sample pairs are CRT‐based colours, and they are selected along the CIELAB L* axis from 0 to 100. The magnitude of colour difference of each pair is 5.0 CIELAB units. The visual assessment results showed that there is a very large crispening effect. The colour differences of the same pair assessed under different backgrounds could differ by a factor of up to 8 for a sample pair with low lightness. The perceived colour difference was enlarged when the lightness of a sample pair was similar to that of the background. The extent of crispening effect and its quantification are discussed in this investigation. The performances of five colour‐difference equations were also tested, including the newly developed CIEDE2000. © 2004 Wiley Periodicals, Inc. Col Res Appl, 29, 374–380, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20045     

Modelling of chromatic contrast for retrieval of wallpaper images

Colour remains one of the key factors in presenting an object and, consequently, has been widely applied in retrieval of images based on their visual contents. However, a colour appearance changes with the change of viewing surroundings, the phenomenon that has not been paid attention yet while performing colour‐based image retrieval. To comprehend this effect, in this article, a chromatic contrast model, CAMcc, is developed for the application of retrieval of colour intensive images, cementing the gap that most of existing colour models lack to fill by taking simultaneous colour contrast into account. Subsequently, the model is applied to the retrieval task on a collection of museum wallpapers of colour‐rich images. In comparison with current popular colour models including CIECAM02, HSI and RGB, with respect to both foreground and background colours, CAMcc appears to outperform the others with retrieved results being closer to query images. In addition, CAMcc focuses more on foreground colours, especially by maintaining the balance between both foreground and background colours, while the rest of existing models take on dominant colours that are perceived the most, usually background tones. Significantly, the contribution of the investigation lies in not only the improvement of the accuracy of colour‐based image retrieval but also the development of colour contrast model that warrants an important place in colour and computer vision theory, leading to deciphering the insight of this age‐old topic of chromatic contrast in colour science. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 361–373, 2015     

Colour appearance rating of familiar real objects

The determination of the long‐term memory colours of objects has been the subject of investigation for many years. Colour acceptance boundaries have been determined from the visual assessments of objects under variable illumination or by presenting manipulated images of objects on a calibrated computer display. However, a systematic and quantitative rating of the colour of real objects with respect to memory colour is not available at this moment. In this article, nine familiar real objects with colours distributed around the hue circle were positioned in a specially designed LED illumination box. For each object, approximately hundred real illumination spectra were synthesized in a random order keeping the luminance of the object approximately constant. Observers were asked to rate, on a five‐point scale, the similarity of the perceived object colour to their idea of what the object looked like in reality. By avoiding specular reflections, the observer was unable to identify any clues as to the colour of the illumination. For each object, similarity ratings showed a good intraobserver and interobserver agreement. The ratings of all the observers were pooled and successfully modeled in IPT colour space by a bivariate Gaussian distribution. It was found that the chromaticity corresponding to the highest rating tended to be shifted toward higher chroma in comparison with the chromaticity calculated under D65 illumination. The bivariate distributions could be very useful in applications where the quantitative evaluation of the colour appearance of an object stimulus is required, such as in the evaluation of the colour rendering capabilities of a light source. © 2010 Wiley Periodicals, Inc. Col Res Appl, 36, 192–200, 2011;     

An investigation of colour appearance for unrelated colours under photopic and mesopic vision

Data were obtained for the colour appearance of unrelated colours under photopic and mesopic conditions. The effects of changes in luminance level and stimulus size were investigated. The method used was magnitude scaling of brightness, colourfulness, and hue. Two stimulus sizes (10° and 0.5°) and four starting luminance levels (60, 5, 1, and 0.1, cd/m²) were used. The results at 0.1 cd/m² had large variations, so data were obtained for two additional stimulus sizes (1° and 2°) at this luminance level. Ten observers judged 50 unrelated colours. A total of 17,820 estimations were made. The observations were carried out in a completely darkened room, after 20 min adaptation; each test colour was presented on its own. Brightness and colourfulness were found to decrease with decreases of both luminance level and stimulus size. The CAM97u model predicted brightness more accurately than CIECAM02 but gave worse performance in predicting colorfulness. For hue, CAM97u and CIECAM02 both gave satisfactory predictions. Using the brightness correlate from CAM97u, a new colour‐appearance model based on CIECAM02 was developed specifically for unrelated colours under photopic and mesopic conditions, with parameters to allow for the effects of luminance level and stimulus size. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2011;     

On the colours dichromats see

Dichromatic colour vision is commonly believed to be a reduced form of trichromatic colour vision (referred to as the reductionist principle). In particular, the colour palette of the dichromats is believed to be a part of the colour palette of the trichromats. As the light‐colour palette differs from the object‐colour palette, the dichromatic colour palettes have been derived separately for light‐colours and object‐colours in this report. As to light‐colours, the results are in line with the widely accepted view that the dichromatic colour palettes contain only two hues. However, the dichromatic object‐colour palettes have proved to contain the same six component colours which constitute the trichromatic object‐colour palette (yellow, blue, red, green, black and white). Moreover, all the binary and tertiary combinations of the six component colours present in the trichromatic object‐colour palette also occur in the dichromatic object‐colour palettes. Yet, only five of the six component colours are experienced by dichromats as unitary (unique) object‐colours. The green unitary colour is absent in the dichromatic object‐colour palettes. The difference between the dichromatic and trichromatic object‐colour palettes arises from the fact that not every combination of the component‐colour magnitudes occurs in the dichromatic object‐colour palettes. For instance, in the dichromatic object‐colour palettes there is no colour with the strong green component colour. Furthermore, each achromatic (black or white) component colour of a particular magnitude is combined with the only combination of the chromatic components. In other words, the achromatic component colours are bound with the chromatic component combinations in dichromats. © 2012 Wiley Periodicals, Inc. Col Res Appl, 39, 112–124, 2014     

Colour meaning and context

This study compares semantic ratings of colour samples (chips) with those of the same colours applied to a variety of objects. In total, 25 participants took part in the colour‐meaning experiment, and assessed 54 images using five semantic scales. In Experiment 1, simplified images (coloured silhouettes) were used whereas in Experiment 2 real images were used. In this article, the terms “chip meaning” and “context meaning” are used for convenience. Chip meaning refers to the associated meanings when only isolated colour chips were evaluated while context meaning refers to colour meanings evaluated when colours were applied to a variety of product categories. Analyses were performed on the data for the two experiments individually. The results of Experiment 1 show relatively few significant differences (28%) between chip meaning and context meaning. However, differences were found for a number of colours, objects, and semantic scales i.e., red and black; hand wash and medicine; and masculine‐feminine and elegant‐vulgar. The results of Experiment 2 show more significant differences (43%) between chip meaning and context meaning. In summary, the context sometimes affects the colour meaning; however, the degree to which colour meanings are invariant to context is perhaps slightly surprising. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 450–459, 2017     

Grids for Assessing Colour Appearance

A technique of subjective magnitude estimation has been used to assess a set of pseudosurface colours, each having a luminance equal to half that of its adapting surround. Five observers scaled each of the colours three times in each of two adaptation conditions corresponding to daylight and tungsten light at 120 cd/m². Loci of constant hue and saturation were derived in u', v' chromaticity space for daylight and tungsten light. These grids enable the appearance of a colour to be specified from a knowledge of its chromaticity coordinates and they enable such effects as colour constancy and colour fidelity to be investigated in terms of perceived colour appearance.     

Food colorants: their past,present and future

Whether we are purchasing fresh vegetables from a market stall, ready meals from the supermarket, eating at home or in a five‐star restaurant, we use colour to tell us what to expect in terms of taste, nutrition and safety. This review considers the techniques that have, over the years, been employed to modify the colour of our food, and the interactions of these techniques with issues of safety and nutrition. The demand for brightly coloured food resulted in the incorporation of some questionable inorganic and organic chemistry being used in food products. A limited number of synthetic dyes are still used in food today, but health concerns and the consumer‐driven demand for natural colorants has brought about a change in the way food is coloured. The proliferation of products with labels that state they contain “No artificial colours” on supermarket shelves suggests that the future of azo dyes and their various derivatives is strictly limited. Nature produces an abundance of colours and many of these are extracted and used as natural food colorants; however, they are subject to application limitations and stability problems. Significant research by academia and industry into methods to stabilise and expand the application possibilities for the various approved natural food colorants is ongoing, but most developments that food colour manufacturers proclaim are enhanced vehicles for delivering established natural pigments into food products.     

A study of colour emotion and colour preference. Part III: Colour preference modeling

In this study three colour preference models for single colours were developed. The first model was developed on the basis of the colour emotions, clean–dirty, tense–relaxed, and heavy–light. In this model colour preference was found affected most by the emotional feeling “clean.” The second model was developed on the basis of the three colour‐emotion factors identified in Part I, colour activity, colour weight, and colour heat. By combining this model with the colour‐science‐based formulae of these three factors, which have been developed in Part I, one can predict colour preference of a test colour from its colour‐appearance attributes. The third colour preference model was directly developed from colour‐appearance attributes. In this model colour preference is determined by the colour difference between a test colour and the reference colour (L*, a*, b*) = (50, ?8, 30). The above approaches to modeling single‐colour preference were also adopted in modeling colour preference for colour combinations. The results show that it was difficult to predict colour‐combination preference by colour emotions only. This study also clarifies the relationship between colour preference and colour harmony. The results show that although colour preference is strongly correlated with colour harmony, there are still colours of which the two scales disagree with each other. © 2004 Wiley Periodicals, Inc. Col Res Appl, 29, 381–389, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20047     

A comprehensive model of colour appearance for related and unrelated colours of varying size viewed under mesopic to photopic conditions

CIE has recommended two previous appearance models, CIECAM97s and CIECAM02. However, these models are unable to predict the appearance of a comprehensive range of colours. The purpose of this study is to describe a new, comprehensive colour appearance model, which can be used to predict the appearance of colours under various viewing conditions that include a range of stimulus sizes, levels of illumination that range from scotopic through to photopic, and related and unrelated stimuli. In addition, the model has a uniform colour space that provides a colour‐difference formula in terms of colour appearance parameters. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 293–304, 2017