Hue Categories Research Articles

Brightness and hue judgment of dyed hair color

This study aims to investigate human hair color perception through two empirical studies in the context of colored hair. The preliminary study was intended to establish a numerical representation of perceptually meaningful brightness levels. It identified that the brightness level was proportional to the power of 0.766 of L*. In the visual assessment, participants (N = 47) categorized 246 hair color samples into eight color hue groups aligned with the Munsell system. Hue judgment was conducted by visually comparing dyed hair tresses with natural black hair. Based on the L*, a*, and b* values of hair tresses and visual assessments thereof, we observed the ranges of hue categories for hair color alongside the brightness levels. Additionally, the differences between the Munsell hue names and the assessment results were compared. Predominantly influenced by the dark brown hair color, the neutral orientation was shifted to the first quadrant of the a*-b* plane. The study contributes to an understanding of human hair color perception and provides insights into color categorization and labeling, especially when the context is confined.

Relative contributions of melanopsin to brightness discrimination when hue and luminance also vary.

A large number of studies have shown the effect of melanopsin-dependent retinal ganglion cells on humans performing brightness discrimination tasks. These studies often utilized targets that only differ in their melanopsin activation levels, and not in their luminance or hue, which are both factors that make large contributions to brightness discrimination. The purpose of the present study was to evaluate the relative contribution of melanopsin activation to brightness discrimination when luminance and hue are also varying in addition to melanopsin activation. Using an apparatus consisting of three separate high luminance projectors, we were able to manipulate melanopsin-isolating stimulation, and L-, M-, and S-cone stimulation separately, thus allowing us to vary stimuli in their melanopsin activation, luminance, and hue category independently. We constructed three sets of target stimuli with three different levels of melanopsin activation (100%, 131%, and 167% relative melanopsin excitation) and five levels of luminance. We then had subjects do a two-alternative forced choice task where they compared the previously described target stimuli set to a set of four comparison stimuli that varied in their hue category but had identical luminances. We found that in our stimuli set the overall contribution of melanopsin activity to brightness discrimination was small (an average of 6% increase in likelihood to call a high melanopsin activity stimulus brighter compared to a low melanopsin activity stimulus) when luminance and hue also varied. However, a significant interaction showed that when the comparison was between stimuli differing only in melanopsin stimulation (with luminance and hue unchanged) the contribution of melanopsin to brightness judgments was about 3 times larger (an average of 18% increase in likelihood to call a high melanopsin activity stimulus brighter compared to a low melanopsin activity stimulus). This suggests that although luminance and hue have large effects on brightness discrimination such that the melanopsin contribution can become hard to detect, when there are minimal cone-dependent signals available, melanopsin can make a large contribution to brightness discrimination.

Optimal display color for nighttime smartphone users

AbstractThe study investigated the optimal display color for comfortable use of smartphones at night under low illuminance, while not distorting the perceived quality of displays. Two phases of psychophysical experiments were conducted to judge perceptibility and acceptability of the displays in various shades of white. The experimental results showed that the scores in acceptability were always higher than those in perceptibility all across the hues, and yellow received the highest scores in acceptability among the six hue categories. This can be interpreted that the observers have the intention of using a display in a yellow shade of white even though it is not perceived as pure white. Through the analysis, a white in yellow shade with the RGB values of 255, 255, and 230 was determined as the optimal display color for nighttime smartphone users regardless of display luminance or contents. The proposed display color supports physiological comfort by reducing the blue light, which involves an adverse effect on the biological system, and provides psychological satisfaction by allowing users to decide the color within the range of the user's acceptable threshold. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 60–67, 2017

Foveal color perception: Minimal thresholds at a boundary between perceptual categories

Human color vision depends on the relative rates at which photons are absorbed by the three classes of retinal cone cell. The ratios of these cone absorptions can be represented in a continuous two-dimensional space, but human perception imposes discrete hue categories on this space. We ask whether discrimination is enhanced at the boundary between color categories, as it is at the boundary between speech sounds. Measuring foveal color discrimination under neutral conditions of adaptation, we find a region of enhanced discrimination in color space that corresponds approximately to the subjective category boundary between reddish and greenish hues. We suggest that these chromaticities are ones at which an opponent neural channel is in equilibrium. This channel would be ‘non-cardinal’, in that its signals would not correspond to either axis of the MacLeod–Boynton chromaticity diagram.

Where Do the Unique Hues Come from?

Where are we to look for the unique hues? Out in the world? In the eye? In more central processing? 1. There are difficulties looking for the structure of the unique hues in simple combinations of cone-response functions like (L − M) and (S − (L + M)): such functions may fit pretty well the early physiological processing, but they don’t correspond to the structure of unique hues. It may seem more promising to look to, e.g., Hurvich & Jameson’s ‘chromatic response functions’; but these report on psychophysical behaviour, not on underlying physiology. So ‘opponent processing’ isn’t any particular help on the unique hues—and even physiology in general seems not to have come up with any good correlate or explanation. 2. Wright (Review of Philosophy and Psychology 2: 1–17, 2011) looks in a different place: to (a) magnitude of total visual response that a stimulus light provokes, the maxima and minima of which, he thinks, give us the boundaries of the main hue categories (Wright connects these with Thornton’s ‘prime’ and ‘antiprime’ colours in an illuminant: Journal of the Optical Society of America 61 (1971): 1155–1163); and (b) the ratio of chromatic to achromatic response, the maxima and minima of which, he suggests, give us the focal points of the unique hues. The suggestions are extremely interesting; but the desired correspondences have some counterexamples; and where they hold, one could wonder how much they depend upon the particular choice of functions to measure (a) and (b); and one could hope for more of an explanatory linkage between the sets of items in question. 3. Could the unique hues come from, so to speak, the external world? White and black can easily be defined as particular kinds of reflectance. What of the standard four unique hues? Variation in kinds of sunlight and skylight coincides well with variation along a line from unique yellow to unique blue (cf. Shepard 1992, Mollon 2006). If we wanted something to calibrate our standards for unique yellow and blue as the lens of the eye changes with age, and despite interpersonal cone differences, this would be a good basis—and there are several ways this can be extended to surface colours. But is there any essential connection between these things: is there any rationale why the light of the sun and the sky should be counted as unique hued? An answer may be: because in our environment, these illuminants are as close to white (or the natural illuminant colour) as you can get—to see things tinged with sunlight or skylight should be to see them minimally tinged with any alien colour. Whereas other hues in an illuminant would be treated as tinging with a more alien colour the thing seen.

More on the Origins of the Hues: A Reply to Broackes

This paper responds to Justin Broackes’ reply to my paper, “On the retinal origins of the Hering primaries.” This paper aims to clarify and further develop the ideas presented in that article. I take up several of the points Broackes raises regarding the connection between my work and that of William Thornton (Journal of the Optical Society of America 61:1155–1163, 1971) and (Color Research and Application 24:139–156, 1999) on the “prime” and “anti-prime” colors of the human visual system, the connection between those prime and anti-prime colors and hue category boundaries, and my attempt to link facts about low-level processing to the unique hues. Ultimately, while Broackes brings up several interesting issues and usefully illustrates the limits of my approach, I see no reason to retreat from the main claims I made about human spectral sensitivity and the hues.

On the Retinal Origins of the Hering Primaries

This paper argues that the distinctiveness of the Hering primary hues—red, green, blue, and yellow—is already evident at the retina. Basic features of spectral sensitivity provide a foundation for the development of unique hue perceptions and the hue categories of which they are focal examples. Of particular importance are locations in color space at which points of minimal and maximal spectral sensitivity and extreme ratios of chromatic to achromatic response occur. This account builds on Jameson and D’Andrade’s (1997) insight about the relationship between the Hering primaries and chromatic/achromatic ratios, Romney and Chiao’s (2009) color appearance model, and Thornton’s (1971, 1999) research on artificial lighting.

Unique Hue Stimulus Choice: A Constraint on Hue Category Formation

AbstractBerlin & Kay hue-related basic color categories are compared with the ISCC-NBS system of object color categorization. Though independently derived, categories of the former form a small subset of the latter. A conjecture is proposed that explains the absence of yellow-green and blue-green basic hue categories and the potential for a violet category as the result of constraints on primitive hue category formation due to considerable variation in stimuli selected by color-normal observers as representing for them unique hues.

Focal Color Variability and Unique Hue Stimulus Variability

AbstractThe degree to which physiology and culture have affected the formation of primitive color categories continues to be a matter of discussion. In this paper the degree of agreement between the ranges of individual color term foci for the four hue-based color categories yellow, green, blue, and red and individual choices of Munsell samples representing for the observers Hering's four unique hues is investigated. The color term focus range data are extracted from the survey results of the 110 unwritten languages of the World Color Survey, also in terms of the Munsell color order system. Agreement of approximately 90% between the two has been found, indicating the likelihood of a strong color vision system related physiological component in the formation of these four primitive hue categories.

Effects of Hue, Value, and Chroma on College Students' Preferences for Apparel and Upholstery Fabrics

To investigate the effects of hue, value, and chroma on college students' color preferences for apparel and upholstery fabrics, experimental conditions were established for evaluation of coded fabric swatches by 118 college students. On a repeated-measures analysis of variance, significant differences were noted among all variables for both conditions. From post hoc tests summer and winter hue categories did not differ for apparel but did for upholstery. Conversely, spring and autumn hue categories did not differ for upholstery but did for apparel. Cool hues were preferred over warm hues for apparel and upholstery. There was no consistent preference for value for apparel and upholstery. For chroma, dull colors were preferred significantly for both apparel and upholstery. Of 20 sets of matched fabrics, only five color preferences for apparel and upholstery fabrics were not significantly different. Overall, color preferences were not equivalent for apparel and for upholstery.

Identification and adaptation of hue: Parallels in the operation of mechanisms that underlie categorical perception in vision and in audition

Four experiments were conducted to examine processes in identification and selective adaptation of hues in color perception that exactly parallel processes in identification and adaptation of auditory detectors that provide information for phonemic perception. The first experiment demonstrated an effect of adaptation on identification of blue and green when a hue category center was used as the adaptor; this experiment also assessed recovery from adaptation. Adaptation to one hue was found to shift identification to favor the alternative hue, implicating a single detector underlying hue categorization. The second experiment demonstrated similar effects of adaptation between green and yellow. The third experiment compared the magnitudes of shift following adaptation with a category center, a near-boundary hue, and variously graded adaptation series. Adaptation was found to be related to the category representativeness of the adaptor(s). Results of the third experiment also provided support for the view that adaptation, rather than response bias, is responsible for shifts in the position of identification functions following extended stimulus exposure. The fourth experiment explored the neural loci of adaptation by an interocular transfer test. Hue adaptation was found to occur at both central and peripheral loci. In the four main experiments, reaction times to identify hues in unadapted and adapted states were also analyzed and compared. Subsidiary experiments assessed the effects of stimulus luminance on the magnitude of adaptation. General principles of categorical perception and its underlying bases, including the sweep, magnitude, and symmetry of adaptation, are discussed. The principal findings of these studies provide new data on hue perception which strikingly parallel findings in speech perception.

Discrimination and matching within and between hues measured by reaction times: some implications for categorical perception and levels of information processing.

Same-different reaction times (RTs) were obtained for pairs of color samples ranging perceptually from blue to green. In Experiment 1, observers responded with “same” if both stimuli in a pair were from the same hue category (i.e., blue-blue or green-green) or “different” if the two stimuli were from different hue categories (i.e., blue-green or green-blue). RT for “same” responses was faster for pairs of physically identical stimuli (A-A) than for pairs of physically different stimuli (A-a) belonging to the same hue. RT for “different” responses was faster for larger physical differences across a boundary between hues (A-B 6 step) than for smaller physical differences (A-B 2 step). Experiment 2 replicated and extended these findings: In one phase observers matched pairs of stimuli as “same” or “different” by categorical similarity as in Experiment 1, and in a second phase observers matched the same stimulus pairs, this time by physical similarity. Matching by categorical similarity replicated the pattern of results found in Experiment 1. Matching by physical similarity showed that RTs for “different” responses were equivalently fast independent of the physical difference between A-B pairs, but were faster for A-B than for A-a comparisons. Further, matching identity was faster under categorical match instructions than under physical match instructions. Results of the two experiments support a model of parallel processing of physical and categorical stimulus information in color perception. Further, these reaction-time data and their implications in color perception (for hues) parallel reaction-time data and their implications in speech perception (for phonemes).

Color vision in the peripheral retina. II. Hue and saturation.

Hue and saturation of spectral lights were measured (direct scaling) in the fovea and at 45 degrees in the periphery; all lights were of equal photopic retinal illuminance (1200 trolands). At each retinal location both large and small targets were used. As shown by previous studies, small peripheral targets appear desaturated and of uncertain hue, except long wavelengths which appear red. However, if target size is increased, saturation increases and a full range of hues is seen; the hue functions for large peripheral targets are comparable to foveal ones for very small targets. From a modified form of color matching, it was concluded that the color deficiency in the periphery is more tritanlike than deutanlike; this is strengthened by the observation, that, for small peripheral targets, hues are generally apportioned between two hue categories and the change from one to the other is at about 580 nm.

The categories of hue in infancy.

Infant looking time was monitored during habituation to the repeated presentation of a wavelength stimulus selected from one basic adult hue category and after a change in stimulation. Recovery from habituation was greater to a wavelength selected from an adjacent hue category than to a wavelength from the same category even though these two stimuli were equally distant (in nanometers) from the habituation wavelength. Differential responding evidenced infants' categorical perception of hue; that is, infants see the physically continuous spectrum as divided into the hue categories of blue, green, yellow, and red. These results help to resolve the long-standing controversy surrounding the primacy of perception over language in the organization of hue.

Color vision and hue categorization in young human infants.

Two studies examined the organization of color perception in 4-month-old human infants. In Study 1, infants looked at selected spectral stimuli repeatedly until their visual attention waned. The stimuli represented instances of basic adult hue categories - blue, green, yellow, and red. Following habituation, infants were shown a series of wavelengths which were the same as or different from the stimuli first seen. Analyses of infant attention during this dishabituation phase of the study indicated that infants categorize wavelengths by perceptual similarity; that is, they see hues in the spectrum much as adults do. In Study 2, a group of infants who looked at the alteration of two wavelengths from the same hue category habituated as did the group of infants who looked at the repitition of a single wavelength from that category, but a group of infants who looked at two wavelengths from different categories habituated at a slower rate. Data from the two studies suggest a high degree of organization of the color world prior to language acquisition.

The Influence of Visual Perception on Culture1

Cultural differences in basic color categorization or nomenclature have been variously explained by biological evolution, linguistic relativism, or semantic evolution. This paper reviews these theories and their implied philosophical antecedents. Furthermore, it brings recent ethological, electrophysiological, behavioral, and psychophysical data to bear on this formerly linguistic question. In both behavioral and psychophysical studies, natural categories of hue have been shown to exist in infrahuman species and in human infants and adults. The psychological salience of selected features of these hue categories in adult and infant humans has been found to correspond to neural functioning in brain. Moreover, recent psychophysiological evidence suggests that certain cultures may vary from a uniform pattern of categorization of basic hues because certain peoples may actually perceive colors differently and therefore categorize them differently.