Chromatic Difference Research Articles

Research on the colour preference and harmony of the two‐colour combination buildings

AbstractThis study used computer software to design building models with selected colour parameters based on a two‐colour pattern combination, which was then presented on a standard computer screen. Further, the two‐colour combination pattern was adopted to prepare building simulation pictures with 153 colour combinations. A total of six hues were extracted based on the Natural Colour System, and there were also 18 colour samples with different lightness and saturation degrees. The results of the study found that hue difference, lightness difference, chroma difference, and total colour difference have a significant effect on harmony. On the other hand, hue difference, chroma difference, and total colour difference have a significant effect on preference. It is worth noting that lightness difference and architectural colour preferences were negatively related. In addition, there was a high correlation between architectural colour harmony and preference.

Measurement of image quality for large‐screen displays based on audience viewing: Overview of standardization and preliminary study on laser projection displays and LED displays

AbstractThe large screens used in stadiums, shopping malls, and movie theaters typically have multiple viewers looking at them simultaneously. The quantification of these displays' image quality would require more considerations of measurements at different locations to satisfy the multiviewing condition. In this paper, we describe the practical implementation method involved in the current standardization activities. Additionally, a vantage point measurement method is studied. In the actual use case scenarios, the vantage point method is more appropriate. This method mimics the viewing behavior of audiences. The displays we measured were laser projection and LED. The method shows validity in both displays. Using the vantage point method, the experimental data show that the existing large displays may have very prominent differences in luminance and chromaticity at different viewing locations.

Visual Discomfort and Variations in Chromaticity in Art and Nature.

Visual discomfort is related to the statistical regularity of visual images. The contribution of luminance contrast to visual discomfort is well understood and can be framed in terms of a theory of efficient coding of natural stimuli, and linked to metabolic demand. While color is important in our interaction with nature, the effect of color on visual discomfort has received less attention. In this study, we build on the established association between visual discomfort and differences in chromaticity across space. We average the local differences in chromaticity in an image and show that this average is a good predictor of visual discomfort from the image. It accounts for part of the variance left unexplained by variations in luminance. We show that the local chromaticity difference in uncomfortable stimuli is high compared to that typical in natural scenes, except in particular infrequent conditions such as the arrangement of colorful fruits against foliage. Overall, our study discloses a new link between visual ecology and discomfort whereby discomfort arises when adaptive perceptual mechanisms are overstimulated by specific classes of stimuli rarely found in nature.

A Novel Shadow Removal Method Based upon Color Transfer and Color Tuning in UAV Imaging

Through the increasing use of unmanned aerial vehicles as remote sensing tools, shadows become evident in aerial imaging; this fact, alongside the higher spatial resolution obtained by high-resolution mounted cameras, presents a challenging issue when performing different image processing tasks related to urban areas monitoring. Accordingly, the state-of-the-art reported works can correct the shadow regions, but the heterogeneity between the corrected shadow and non-shadow areas is still evident and especially noticeable in concrete and asphalt regions. The present work introduces a local color transfer methodology to shadow removal which is based on the CIE L*a*b (Lightness, a and b) color space that considers chromatic differences in urban regions, and it is followed by a color tuning using the HSV color space. The quantitative comparison was executed by using the shadow standard deviation index (SSDI), where the proposed work provided low values that improve up to 19 units regarding other tested methods. The qualitative comparison was visually realized and proved that the proposed method enhances the color correspondence without losing texture information. Quantitative and qualitative results validate the results of color correction and texture preservation accuracy of the proposed method against other published methodologies.

Can the Dynamic Colouration and Patterning of Bluelined Goatfish (Mullidae; Upeneichthys lineatus) Be Perceived by Conspecifics?

Bluelined goatfish (Upeneichthys lineatus) exhibit dynamic body colour changes and transform rapidly from a pale, buff/white, horizontally banded pattern to a conspicuous, vertically striped, red pattern when foraging. This red pattern is potentially an important foraging signal for communication with conspecifics, provided that U. lineatus can detect and discriminate the pattern. Using both physiological and behavioural experiments, we first examined whether U. lineatus possess visual pigments with sensitivity to long (“red”) wavelengths of light, and whether they can discriminate the colour red. Microspectrophotometric measurements of retinal photoreceptors showed that while U. lineatuslack visual pigments dedicated to the red part of the spectrum, their pigments likely confer some sensitivity in this spectral band. Behavioural colour discrimination experiments suggested that U. lineatuscan distinguish a red reward stimulus from a grey distractor stimulus of variable brightness. Furthermore, when presented with red stimuli of varying brightness they could mostly discriminate the darker and lighter reds from the grey distractor. We also obtained anatomical estimates of visual acuity, which suggest that U. lineatus can resolve the contrasting bands of conspecifics approximately 7 m away in clear waters. Finally, we measured the spectral reflectance of the red and white colouration on the goatfish body. Visual models suggest that U. lineatus can discriminate both chromatic and achromatic differences in body colouration where longer wavelength light is available. This study demonstrates that U. lineatus have the capacity for colour vision and can likely discriminate colours in the long-wavelength region of the spectrum where the red body pattern reflects light strongly. The ability to see red may therefore provide an advantage in recognising visual signals from conspecifics. This research furthers our understanding of how visual signals have co-evolved with visual abilities, and the role of visual communication in the marine environment.

Color mismatch and observer metamerism between conventional liquid crystal displays and organic light emitting diode displays, Part II: Adjacent stimuli with a larger field of view

In part I of this study [Opt. Express 29, 12292 (2021)10.1364/OE.418675], 50 human observers matched the color appearance of six color stimuli produced by four smartphone displays, including one conventional liquid crystal display (LCD) and three organic light emitting diode (OLED) displays, to those produced by a reference smartphone OLED display. The matching and reference stimuli had a field of view (FOV) around 4.77° and were 5.72° apart. In this experiment, we carefully designed and built a new apparatus to make the two stimuli adjacent to each other with an FOV around 20.2°. This not only made the viewing condition in the experiment similar to the typical viewing condition of smartphone displays, but also allowed for an easier color matching, resulting in smaller intra- and inter-observer variations. The performance of the four CMFs, however, were not significantly changed with the increase of the FOV. The CIE 2006 2° CMFs still had the best performance in characterizing the color matches, which did not support the recommendation of using 10° CMFs for stimuli with an FOV beyond 4°. Meanwhile, for the pairs of stimuli with matched color appearance, the LCD display always had the greatest chromaticity differences and degrees of observer metamerism among the four displays, regardless of the CMFs. In particular, the chromaticities of the stimuli produced by the LCD display were always shifted towards the -u’+v’ direction in the CIE 1976 u’v’ chromaticity diagram, when calculated using the CIE 1931 CMFs. This implies that the neutral colors shown on LCD displays would have a yellow-green tint on OLED displays, if they were calibrated to the same chromaticities using the CIE 1931 2° CMFs.

Color space influence on ANN skin lesion classification using statistics texture feature

This study aims to investigate the ability of an artificial neural network to differentiate between malign and benign skin lesions based on two statistics terms and for RGB (R red, G green, B blue) and YIQ (Y luminance, and I and Q chromatic differences) color spaces. The targeted statistics texture features are skewness (S) and kurtosis (K) which are extracted from the histograms of each color channel corresponding to the color spaces and for the two classes of lesions: nevi and melanomas. The extracted data is used to train the Feed-Forward Back Propagation Networks (FFBPNs). The number of neurons in the hidden layer varies: it can be 8, 16, 24, or 32. The results indicate skewness features computed for the red channel in the RGB color space as the best choice to reach the goal of our study. The reported result shows the advantages of monochrome channels representation for skin lesions diagnosis.

Spectral reflectance and chromaticity differences of various colors of interior finishing material samples under tunable LED lamps

The appearance of objects in interior lighting scenarios is determined by spectral characteristics of the light sources and of the interior finishing material surfaces. Within recent developments of tunable LED lamps, it is possible to vary the correlated color temperature (CCT) of the sources; however, it is relatively unknown whether such variations shall also shift the color appearance. Therefore, this study aims to identify and to analyze the spectral reflectance and chromaticity differences of various colors of interior finishing samples under a tunable LED lamp with varying CCT. The chromaticity coordinates were estimated from the spectrally reflected exitance, under the CIE standard illuminant E and a tunable LED lamp with 10 CCT values (2000–6500 K). Ten samples of painted plywood and wallpapers of various colors were tested. Spectral reflectance of the painted plywood and wallpaper with yellow, beige, red, pink, brown colors can be accurately measured under the tunable LED with CCT 5000 K. Meanwhile, dark blue, dark green, light green, gray, light gray colors are best to be measured under CCT 5500 K. The smallest difference of chromaticity coordinate (Δu'v' = 0.117) is obtained for the light green color sample, meaning that its color appearance is the least likely to change when illuminated by LED lamp with varying CCT. The key contribution is the method to determine the characteristics of interior finishing materials with different colors, observed under tunable LED lamps. The findings can be applied as guideline to optimize objects color appearance in various interior lighting scenarios.

Impact of Packaging Film and Beef Trimmings on Ground Beef Shelf Life.

Fresh beef storage in the retail setting can be presented in a variety of packaging methods, and identifying an alternative such as vacuum packaging to current traditional methods could potentially increase shelf life and reduce meat waste. The objective of this study was to identify the influence of packaging film and lean trimming sources on fresh ground beef surface color during a simulated retail display period. There were no differences (p > 0.05) in surface color redness (a*), yellowness (b*), chroma, or hue angle regardless of packaging film or lean trimmings. However, thiobarbituric acid reactive substances (TBARS) were greater (p < 0.05) for packages containing a greater percentage of CULL beef trimmings regardless of packaging film. In addition, pH values of ground beef packages did not differ (p > 0.05) among packaging film or lean trimming blends. Visual color did not differ (p > 0.05) throughout the simulated retail display period regardless of beef trimmings or packaging film. Microbial spoilage organisms were greater (p < 0.05) after the simulated display period. These results suggest that ground beef presented in a simulated retail setting using an alternative packaging platform, such as vacuum packaging, is plausible.

True-Color Reconstruction Based on Hyperspectral LiDAR Echo Energy

With the development of remote sensing technology, the simultaneous acquisition of 3D point cloud and color information has become the constant goal for scientific research and commercial applications in this field. However, since radar echo data in practice refer to the value of the spectral channel and its corresponding energy, it is still impossible to obtain accurate tristimulus values of the point through color integral calculation after traditional normalization and multispectral correction. Furthermore, the reflectance of the target, the laser transmission power and other factors lead to the problems of no echo energy or weak echo energy in some bands of the visible spectrum, which further leads to large chromatic difference compared to the color calculated from the spectral reflectance of standard color card. In response to these problems, the hyperbolic tangent spectrum correction model with parameters is proposed for the spectrum correction of the acquired hyperspectral LiDAR in the 470–700 nm band. In addition, the improved gradient boosting decision tree sequence prediction algorithm is proposed for the reconstruction of missing spectrum in the 400–470 nm band where the echo energy is weak and missing. Experimental results show that there is relatively small chromatic difference between the obtained spectral information after correction and reconstruction and the spectrum of standard color card, achieving the purpose of true color reconstruction.

Substituent-Adjusted Electrochromic Behavior of Symmetric Viologens.

As a promising electrochromic material, viologens have attracted increasing attention due to their high redox activity and adjustable electrochromic capability. In order to investigate the effect of alkyl substituents on electrochromic behavior, four alkyl-substituted viologens and a benzyl-substituted viologen were synthesized, namely 1,1′-dioctyl-4,4′-bipyridinium dibromide (OV), 1,1′-didekyl-4,4′-bipyridinium dibromide (DeV), 1,1′-didodecyl-4,4′-bipyridinium dibromide (DoV), 1,1′-dihexadecyl-4,4′-bipyridinium dibromide (HV), and 1,1′-dibenzyl-4,4′-bipyridinium dibromide (BV). The different photophysical and electrochemical properties of these viologens were attributed to their deviation in spatial structure caused by different substituents. Compared with benzyl-substituted BV, a slight blueshift occurred for the absorption peaks of alkyl-substituted viologens from 262 to 257 nm with the increase in alkyl chain length. Moreover, the first redox couple increased positively, and the dimerization of the compound decreased gradually, accompanied by the decrease in optical contrast and distinct chromatic difference. A comparison of chromatic and optical contrasts indicated that OV had the longest coloring response time (RTc), while it was shortest for HV. The bleaching response time (RTb) of viologen films gradually decreased with the alkyl chain length, and the OV film had the shortest RTb. Furthermore, when increasing the length of the alkyl chain, the cycling stabilities of alkyl viologens increased gradually. In addition, the OV film exhibited the best contrast after 200 continuous cycles.

Characterization of spray-dried Gac aril extract and estimated shelf life of β-carotene and lycopene.

BackgroundFresh Gac (Momordica cochinchinensis) fruit is rich in carotenoids, mainly β-carotene and lycopene, but these compounds are sensitive to degradation. Spray drying is used to encapsulate the sensitive β-carotene and lycopene with different materials. Only a few reports of using highly branched cyclodextrin (HBCD) have been published. Additionally, studies of β-carotene and lycopene losses in Gac powders during storage are limited. Therefore, the encapsulation of β-carotene and lycopene of Gac aril with HBCD by spray drying at different inlet temperatures were compared. The shelf life of β-carotene and lycopene during storage was also calculated.MethodsThe fresh Gac aril was separated and kept frozen before the experiment. Gac aril and water (1:5 w/v) were centrifuged at 8,000 g at 20 °C for 15 min using a high-speed centrifuge (Sorval; Dupont, Wilmington, DE, USA). The supernatant was filtered twice and concentrated until 15° Brix using a rotary evaporator (R-200; Buchi, Flawil, Switzerland). The mixture of concentrated aril extract and highly branched cyclodextrin at 5% (w/v) was dried at three inlet temperatures by a spray dryer (B-290; Buchi, Flawil, Switzerland) with drying air flow rate, compressor air pressure, and feed rate set at 473 L/h, 40 m3/h, and 3 mL/min, respectively . The physicochemical qualities, particle image morphology, and estimated storage time of β-carotene and lycopene were determined.ResultsIncreased inlet temperatures of spray drying decreased the bulk density, β-carotene, and lycopene content of spray-dried powders significantly. The color values of dried powders had significant differences in yellowness (b*) and chroma, but not lightness (L*), redness (a*), and hue when the inlet temperature increased from 160 °C to 180 °C. The maximum reduction of β-carotene and lycopene observed during storage at 55 °C was 90.88% and 91.11% for 33 and 18 days. For β-carotene, the estimated shelf-life (retention of 50% of β-carotene) was 9.9, 48.4, and 91.6 days at 25 °C, 10 °C, and 4 °C. The shelf-life of lycopene was 26, 176, and 357 days at 25 °C, 10 °C, and 4 °C, respectively. HBCD could be potentially used as an encapsulating agent in spray-dried Gac aril, but the shelf-life of β-carotene and lycopene needs to be improved to be useful as a food ingredient.

무늬 관엽식물 선호도의 변화 및 색채 조화미 분석 - 최근 유통되는 무늬 관엽식물을 중심으로

In this study, we comparatively analyzed the preference of pattern foliage plants to provide the basic data for the status of current use of pattern foliage plants by researching and analyzing changes in the preference of such plants in the years 2010 and 2020. We also analyzed the color-harmonious beauty of pattern foliage plants currently distributed in the market. This study targeted 18 species used for a survey on the preference of pattern foliage plants, and eight species of pattern foliage plants in 2020. For the research and analysis of preference, three surveys were conducted. For the measurement of plant color, the plants were domesticated in a greenhouse (shading rate: approximately 40%) for a week. After taking a photograph of each individual plant in a light room on the basis of day light, the color was measured by correcting it to a standard color using the Adobe Photoshop Program. The results of analyzing the preference of pattern foliage plants using the above method were as follows. Firstly, it was clear that the preference of green-patterned plants was higher than that of red-patterned plants. Secondly, in the plants with red and yellow patterns, the preference was low when the brightness difference was larger. In plants with the same green patterns, the preference was shown regardless of the brightness difference. Moreover, when the difference in chroma was greater, the preference was low. Thirdly, color had the highest influence on the preference of plants. In the case of pattern plants with the same group of colors, the form of pattern and color arrangement rate had a higher influence on the preference than color. As the preference of plants is different at different times, and the preference should be quickly understood to use it for marketing strategies, there should be continuous research on the preference of plants in the future.

Short-wavelength visual sensitivity and sexual differences in plumage colouration of ovenbirds (Aves: Furnariinae)

Ovenbirds represent a clade of exclusively Neotropical birds that are exceptionally diverse, despite their rather dull, melanin-based plumage. In general, sexes are considered monomorphic in size and colour, but several authors have reported females of some species within this family as being slightly paler than their conspecific counterparts. Our aim was to assess levels of sexual dichromatism in a set of ovenbird species representing a diversity of genera and plumage patterns; Furnarius rufus, Phleocryptes melanops, Synallaxis spixi and Schoeniophylax phryganophilus. For each species, we quantified sexual differences in brightness and colouration among 8–10 different plumage regions through modelling avian perceptual colour-space distances. To best inform our visual modelling parameters, we successfully sequenced the SWS1 gene fragment (associated with short-wavelength, including ultraviolet, visual sensitivity in birds) for one species, P. melanops, and found it possessed an amino acid sequence consistent with the VS-type SWS1 visual system. This provides further evidence supporting the presence of VS-sensitive opsin in ovenbirds. Among all four species, females were consistently brighter than males in at least one plumage patch, but chromatic colour differences between sexes were significant only for the throat patches of Schoeniophylax phryganophilus. Overall, we interpret ovenbirds to exhibit very low levels of sexual dichromatism, manifest mainly by achromatic colour differences.

Interpopulation variation in sexual dichromatism in the Neotropical grasshopperSphenarium purpurascens(Orthoptera: Pyrgomorphidae)

AbstractCryptic coloration is an adaptative defensive mechanism against predators. Colour patterns appear cryptic through general background coloration matching or disruptive coloration. Disruptive coloration might evolve in visually heterogeneous microhabitats, whereas background matching could be favoured in chromatically homogeneous microhabitats. In this study, we used digital photography to explore the potential use of disruptive coloration and background matching in males and females of the Neotropical grasshopper Sphenarium purpurascens in different habitats. We found chromatic differences in three habitats and sexual dichromatism that might be explained by local adaptation. Although females and males were sexually dichromatic, interpopulation differences were found in the magnitude of the sexual dichromatism. In a highly contrasting environment, both males and females seemed to follow a disruptive strategy, whereas in a heterogeneous environments males and females followed different colour cryptic strategies, in which males were more disruptive than females, and females exhibited high background matching with fewer disruptive elements. Selective predation in different microhabitats and differences in mobility between the sexes might explain the colour pattern divergence between females and males.

Optimization of conventional and ultrasoundassisted extraction of Paeonia officinalis anthocyanins, as natural alternative for a green technology of cotton dyeing

Plant pigments gained popularity over synthetic dyes because of safety issues regarding the impact on health and environment. The present paper deals with optimization of anthocyanins extraction from Paeonia officinalis L. flowers and their application in cotton eco-dyeing processes. The results on extraction and mathematical models indicate improved extraction by ultrasonication at high solvent/solid ratio (50/1) compared to that by maceration. Among the investigated extraction solvents, the most efficient was 70% ethanol. Cotton dyeing was performed via conventional procedure and ultrasonication, in the presence and absence of classic mordant (copper sulphate) and biomordants (tannic and citric acids). A successful dyeing was obtained according to ATR-FTIR analysis of mordanted dyed samples. The colour properties of dyed cellulosic substrates as determined by CIELAB system showed higher redness values and large positive differences in chroma in samples dyed with peony extract by exhaustion in presence of high concentration of citric acid.

No association between candidate genes for color determination and color phenotype inHierophis viridiflavus,and characterization of a contact zone

Genetic and phenotypic differentiation in allopatric conditions can be explained either by neutral phenomena or adaptative processes driven by selection. In reptiles, coloration can affect aspects directly related to their survival, representing a classical character under selection. In this context, secondary contact areas are natural laboratory to understand evolutionary processes underlying genetic permeability, especially when populations differ in phenotypic traits such as coloration. The western whip snake Hierophis viridiflavus presents two divergent mitochondrial clades, characterized by the presence of one of two main color phenotypes, namely one with black and yellow stripes and a fully melanic one. Here, we investigated whether melanogenesis-linked genes are determinant of the chromatic differences observed across the phenotypic variation of the species. In addition, we used a multilocus dataset, including 134 original ND4 sequences, to better define the overall genetic structure and to provide a characterization of a contact zone identified in Central Italy by estimating the amount of nuclear gene exchange. While we found no evidence supporting a direct association between target genes and coloration, a non-synonymous substitution polymorphism, at high frequency, was detected in the β melanocyte-stimulating hormone whose possible function has been discussed. Concerning the genetic structure, both mtDNA and nuDNA were partly concordant indicating introgression events occurring at the contact zone. When we measured the nuclear gene flow, we found a significant amount of gene exchange, mainly guided from one clade to the other, that is, asymmetric. These results might suggest the presence of ecological and/or behavioral processes driving the observed directional gene flow.

Effects of UV Radiation on Paper: A Chromatic Study

A study on Whatman #1, bond, rice, kraft, and amate papers in their original condition and exposed to 2.25, 4.5, 6.75, and 9 W of Ultraviolet-C radiation is presented. The techniques used were scanning electron microscopy+energy dispersive X-ray spectrometry (SEM+EDS), differential scanning calorimetry+thermogravimetric analysis (DTC+TGA), Fourier transform infrared spectrometry (FTIR), X-ray diffraction (XRD), Ultraviolet/Visible (UV/Vis) spectrophotometry, pH measurements, and colorimetry. No changes were found in these papers, length and width of fibers, chemical composition, pH, pyrolysis characteristics, or FTIR and XRD patterns after irradiation. Cellulose (all papers), calcite (bond, rice, and kraft), whewellite (amate), and kaolinite (kraft) were the main components. Non-irradiated bond paper showed a specular effect on the UV spectra, which was progressively reduced by the UV radiation and becoming almost imperceptible at &gt;6 W. Visible spectra of amate paper showed the presence of β carotenoids and chlorophylls, which are degraded by UV radiation. Visible spectra of Kraft paper showed a color reversion at 2.25 W, which progressively diminished as a function of the UV rate energy transfer. UV radiation gradually clarified amate paper. To make a comparison, kraft and amate paper were exposed to gamma radiation at 3, 9, and 15 kGy. The color of Kraft paper was clarified, and amate paper increased in yellowness. Perceptions of chromatic differences due to gamma radiation were smaller than those observed with UV radiation; however, they are still important, especially for kraft paper.

Longitudinal Chromatic Aberration in Patients Implanted With Trifocal Diffractive Hydrophobic IOLs.

To measure the in vivo longitudinal chromatic aberration (LCA) from the chromatic difference of focus (480 to 700 nm) using psychophysical methods in patients bilaterally implanted with a hydrophobic trifocal intraocular lens (IOL). Psychophysical best focus was measured in both eyes at different wavelengths (480 to 700 nm) and at three different viewing distances (0.00, +1.75, and +3.50 diopters [D]) using a custom-developed polychromatic adaptive optics set-up provided with a supercontinuum laser, a Hartmann-Shack wavefront sensor, a deformable mirror, a motorized Badal system, a pupil monitoring system, and a psychophysical channel with monochromatically illuminated stimuli. Measurements were performed on 10 patients (20 eyes) bilaterally implanted with hydrophobic trifocal diffractive IOLs (FineVisionHP POD F GF; PhysIOL). LCA was computed from the chromatic difference of focus curves as the difference between 480 and 700 nm at near, intermediate, and far. The LCA from psychophysical measurements was significantly higher for far vision (0.99 ± 0.06 diopters [D]), than for intermediate (0.67 ± 0.10 D) and near (0.23 ± 0.08 D) vision (one-way analysis of variance, P < .05). LCA for far vision was significantly higher than for intermediate and near vision in hydrophobic trifocal diffractive IOLs, in agreement with a previous study with the same optical design but hydrophilic material IOLs. The LCA for the hydro-phobic IOL is slightly higher than for the hydrophilic IOL at far. Different combinations of refractive and diffractive LCA will allow optimizing IOL designs to improve polychromatic image quality. [J Refract Surg. 2020;36(12):804-810.].

Effect of Hairiness on Fabric Colour Characteristics

Designing the colour appearance of textiles requires taking into account their surface properties, hairiness among others. The villi protruding on the surface not only affect the quality of textile dyeing, but also largely determine its optical properties and the colour phenomenon. The analysis of studies of optical properties shows that the influence of hairiness on the phenomenon of colour is not well understood and that the amount of hairiness at which colour changes become significant for human perception remains indefinable. In this work, we studied the change in colour characteristics depending on the change in the hairiness of woollen fabrics, comparing “yarn – raw fabric”, “yarn – raised fabric”, “raw fabric – raised fabric”. Hairiness was estimated by the hairiness index, which was obtained from the analysis of sample microphotographs of yarn and fabric using software. The value of colour characteristics (lightness, chroma and colour difference) was measured in the CIELAB colour space (1976) using a spectrophotometer. The obtained experimental results showed that the changes in lightness and saturation of textile materials from the index of its hairiness are directly proportional. However, the value of changes is different for raw and napped fabrics, undyed and dyed samples, the initial colour hue and raw material composition also making certain adjustments. This study analysed the colour difference and established the level of variation in hairiness at which the colour mismatch between woollen fabrics becomes visually noticeable. The results of the study can be used to predict the colour and design the optical properties of fabrics for weaving and finishing.