Conditions Of Chromatic Adaptation Research Articles

Bongard and Smirnov on the tetrachromacy of extra-foveal vision

In Moscow in the 1950′s, the physicist M. M. Bongard developed the use of silent substitution to establish the number of dimensions of human or animal colour vision and to derive colour-matching functions either for whole organisms or for individual neuronal channels. In 1956, he and his colleague M. S. Smirnov reported that extra-foveal human vision was tetrachromatic when tested by the silent-substitution method that they called ‘replacement colorimetry’. In the steady state, trichromatic matches were possible in extra-foveal regions, but transients were visible when one such match was replaced by another. If, however, a match was made with four primaries, then a silent substitution was possible; and such matches – unlike trichromatic ones – were stable with light level and with changes in the state of chromatic adaptation. Bongard and Smirnov believed that the fourth receptor had the spectral sensitivity of the rods, but of course they were working long before the discovery of intrinsically photosensitive retinal ganglion cells. On the fiftieth anniversary of Bongard’s grievous death, we provide a translation of Bongard and Smirnov’s paper on the tetrachromacy of extra-foveal vision. In a commentary, we give the background to their work and provide further details of their apparatus and procedure. We briefly discuss related research and the reception in the West of Bongard and Smirnov’s claims. We suggest that an analogy can be made between the tetrachromacy of the parafovea and the ‘weak tetrachromacy’ of heterozygotes for anomalous colour vision, whose trichromatic matches are not stable with chromatic adaptation.

Von‐Kries‐enhanced chromaticity gamut

AbstractThis note describes a way of extending the physical lights inside the spectrum locus to supersaturated colors related to them by a Von Kries transformation. The extension is one‐way but quantitative: One can see a supersaturated light in a given state of chromatic adaptation, and one can compute its chromaticity through a proportion based on three physical lights, but one cannot further connect the perception and the computed chromaticity to test the adaptation model that is used to make the construction. The construction may nonetheless be useful in delimiting the chromaticities that are computed as intermediate states in a color‐management system.

What sets the state of chromatic adaptation?

What sets the state of chromatic adaptation?

Chromatic adaptation to illumination investigated with adapting and adapted color

AbstractThe state of chromatic adaptation was investigated by using the two‐room technique. This technique involves a subject in a room who looks a white board in a separate test room through a window and judges the color of the window using the elementary color naming method. When the subject room is illuminated with a colored light and the test room with a white light, the window appears to be a very vivid color, for which the apparent hue depends on the color of the subject room. The color is referred to as the adapted color. The subject also evaluated the appearance of the illumination color of the subject room, which is called the adapting color. Two types of illuminating light in the subject room, fluorescent lamps with 7 colors and LED lamps with 19 colors, were employed. The adapting and the adapted colors were plotted on a polar diagram that was used in the opponent color theory, from which the hue angles were obtained. The hue angle difference between the two colors did not appear to be 180° except for one pair of adapting and the adapted colors, which implies that chromatic adaptation does not follow the opponent color concept. An improvement was achieved to explain the results by introducing complementary colors relation between the adapting and adapted color.

Color discrimination subject to illuminant and color transition

AbstractDue to technological influence on the production process there are variations of the chromaticity coordinates that may cause visible differences of the perceived color of LEDs of the same production batch. To minimize the negative impact of such variations for the user the manufacturers carry out colorimetric measurements of LEDs and sort them into tolerance groups of similar chromaticity coordinates. The corresponding groups are defined by their respective center point surrounded by a quadrangular tolerance limit whereas the tolerance limits are based on tolerance ellipses gained in the 1940s by MacAdam. However, due to another scientific target of MacAdam's experiments, applying his ellipses as a base for grouping the chromaticity coordinates has to be questioned. With a view toward a method for grouping according to chromaticity coordinates for white LEDs with phosphor conversion, the results of research with test subjects regarding their discrimination and magnitude perception of chromatic differences are presented. In this research three chromaticities with the correlated color temperatures of 2700, 4000, and 6500 K and variations of color transitions are investigated, which match realistic luminaire designs for practical applications. The empirically determined thresholds are expanded according to the transformation to different chromatic adaptation conditions as per von Kries that are then compared to the results by MacAdam and the influence on adaptation is being discussed. A new concept for the calculation of tolerance limits for LED binning is presented. © 2015 Wiley Periodicals, Inc. Col Res Appl, 41, 457–467, 2016

Distinct Mechanisms Mediate Visual Detection and Identification

A core organizing principle for studies of the brain is that distinct neural pathways mediate distinct behavioral tasks [1, 2]. When two related tasks are mediated by a common pathway, studies of one are likely to generalize to the other. Here, we test whether performance on two laboratory tasks that model object detection and identification are mediated by common mechanisms of visual adaptation. Although both tasks rely on the luminance pattern in images, their demands on visual processing are quite different. Object detection requires discriminating image luminance differences associated with the light reflected from adjacent objects. To encode these differences reliably, neurons adapt their limited dynamic range to prevailing viewing conditions [3-6]. Object identification, on the other hand, demands a fixed response to light reflected from an object independent of illumination [7]. We compared performance in discrimination and identification tasks for simulated surfaces. In striking contrast to studies with less structured contexts, we found clear evidence that distinct processes mediate judgments in the two tasks. These results challenge models that account for perceived lightness entirely through the action of image-encoding mechanisms.

Spectral correspondence between visual spectral sensitivity and bioluminescence emission spectra in the click beetle Pyrophorus punctatissimus (Coleoptera: Elateridae)

The presence of two spectral mechanisms, near-ultraviolet and green ( λ max=545 nm), is strongly suggested by electroretinographic visual spectral sensitivity curves obtained under dark and red chromatic adaptation conditions in the compound eyes of the click beetle Pyrophorus punctatissimus. The bioluminescence emission of the dorsal prothoracic lanterns is deep green ( λ max=543 nm) and that of the ventral abdominal lantern is lime green ( λ max=556 nm) in colour in P. punctatissimus. A broad green visual receptor would detect both deep green and lime green bioluminescent optical signals.

Adaptive shift of visual sensitivity balance under ambient illuminant change.

We examined the relationship between the ambient illuminant chromaticity and changes in the sensitivity balance of the visual system, using illuminants of various chromaticities. The sensitivity of observers was measured in a room with a variable-chromaticity illuminant. The observer's state of chromatic adaptation was measured with unique-white settings. Our results showed that the change in visual sensitivity has a nonlinear correlation with the change in illuminant chromaticity; chromatic adaptation was nearly complete for desaturated illuminants, but the degree of chromatic adaptation became worse as the illuminant became more saturated. We defined a new index, relative cone weights, which represents this relationship well. To measure the role of chromatic induction from the immediate-surround area of the matching stimulus, we performed additional experiments by presenting the test inside a colored or black immediate surround. The results showed that the unique-white settings were not disturbed by the change in immediate-surround color. Our results imply that the room illuminant chromaticity was the primary factor in changing the observer's state of chromatic adaptation.

ERG measurements of the spectral sensitivity of common chimpanzee (Pan troglodytes).

The spectral sensitivity of the common chimpanzee (Pan troglodytes) was measured with electroretinogram (ERG) flicker photometry. Chromatic adaptation conditions were used to establish the presence of S-, M- and L-cone pigments. Each of 26 chimpanzees showed substantial and approximately equivalent adaptational changes over the middle and long wavelengths implying an absence of any significant polymorphic variations in the M- and L-cone pigments. As inferred from ERG measurements, the S-cone pigment of the chimpanzee has a spectral peak of about 430 nm. Chimpanzee spectral sensitivity measurements were compared to those obtained from equivalently tested normal human trichromats. The spectral sensitivity of the two species is very similar, chimpanzees being slightly more sensitive to short wavelength lights and slightly less sensitive to long wavelength lights than human subjects. Curve-fitting analyses suggest that spectral filtering may be lower in the chimpanzee lens than it is in the human lens, and that the L/M cone ratio is lower in the chimpanzee.

Cathode-ray-tube to reflection-print matching under mixed chromatic adaptation using RLAB

Color-appearance models are used to relate chromatic stimuli viewed under one set of viewing and illuminating conditions to a differing set such that when each stimulus is viewed in its respective conditions, the stimuli match in color appearance. These models assume the observer has a steady-state adaptation to each condition. In practice, observers often view stimuli under mixed adaptation; this could occur when viewing CRT and reflection-print stimuli simultaneously. A visual experiment was performed to determine whether the RLAB color-appearance model could be used successfully to generate reflection prints that match the appearance of the CRT when viewed under mixed states of adaptation and in turn as stand-alone images viewed under a single state of adaptation. Sixteen observers viewed four pictorial images displayed on a D 65 balanced CRT display in a room lit with cool-white fluorescent luminaries. The RLAB color-appearance model was used to calculate corresponding images where the observer's state of chromatic adaptation was assumed to be one of the following: adaptation to each device condition, a single adaptation at the midpoint of the two device conditions, adaptation to the CRT condition and a print adaptation shifted 25% toward the CRT condition, adaptation to the print condition and a CRT adaptation shifted 25% toward the print condition, and a CRT condition shifted 25% toward the print condition and a print condition shifted 25% toward the CRT condition. Each condition was compared pairwise and Thurstone's law of comparative judgments was used to calculate interval scales of quality. Observers first judged the reflection prints adjacent to the CRT display selecting the image closest in color appearance to the CRT image; they also categorized the closest image as marginally acceptable, or not acceptable. The images were again scaled except the display was turned off; this determined the best standalone color reproduction.

Detection of blue under chromatic adaptation: The effects of stimulus size and eccentricity

We measured thresholds for the perception of blue under chromatic adaptation to white, green, yellow or red at the eccentricities of 0–70 deg in the temporal visual field of four subjects. We used a series of stimulus sizes at each eccentricity, without a prior assumption of any peripheral size-scaling factor. The CIE 1976 UCS ( u′, v′) chromaticity coordinates corresponding to blue perception were subtracted from the chromaticity coordinates of the adaptation field in order to obtain the threshold differences (d u′, d v′) in chromaticity coordinates. Spatial scaling factors for the perception of blue were obtained by non-linear regression. ( E 2 + 5 deg) refers to the eccentricity at which stimulus diameter had to be doubled in order to maintain performance found at the eccentricity of 2.5 deg. E 2 for the perception of blue tint varied from 1.2 to 36 deg depending on the state of chromatic adaptation and subject. For the perception of blue tint in yellow three subjects and for the perception of blue tint in red one subject had no spatial scaling factor that would make performance independent of eccentricity. Thus, spatial scaling does not always work.

Perception of Green and Red Under Chromatic Adaptation: The Effects of Stimulus Size and Eccentricity

We measured thresholds for the perception of green and red light added to white, blue, green, yellow, or red adaptation fields presented at eccentricities of 0 to 70 degrees in the temporal visual field of two subjects. A series of stimulus sizes was used at each eccentricity to determine size-scaling factor E2--the eccentricity at which stimulus diameter has to be doubled in order to maintain foveal performance. For green light added to white or yellow, E2 varied from 3.1 to 41.5 degrees. When red light was added to white, yellow, or blue, E2 varied from 0.1 to 11.8 degrees. For red color in green and green color in blue or red there was no spatial scaling factor that would make performance independent of eccentricity. Our results suggest that E2 value for green and red perception depends on the state of chromatic adaptation and also shows marked interindividual differences.

Luminance.

Luminance was introduced by the CIE as a photometric analog of radiance. This implies that an additive spectral-luminosity function characterizes the human observer. In practice, many different spectral-sensitivity functions characterize human vision, although few produce the additive spectral-luminosity function V (lambda), which is suitable for use in practical photometry. Methods that give rise to additive spectral-sensitivity functions that most resemble V (lambda) tend to have in common the use of spatial or temporal frequencies that will discriminate against signals from the short-wavelength-sensitive cone pathways or against signals in other chromatic pathways. Some of the difference among results obtained with different techniques seems to reflect the extent to which the methods can bring about changes in the state of chromatic adaptation, but it also seems likely that not all tasks tap the same postreceptoral mechanisms. Psychophysical evidence is equivocal regarding the nature of the postreceptoral mechanisms: some evidence suggests just three mechanisms, one of which has a spectral sensitivity that is like V (lambda); other evidence suggests the existence of multiple mechanisms with different spectral sensitivities. Physiological recordings from neurons in the macaque's visual pathway suggest that the properties of the magnocellular system may be sufficient to account for spectral-sensitivity functions measured with the techniques of heterochromatic flicker photometry, minimally distinct border, and critical flicker fusion. These are the psychophysical methods that yield spectral sensitivities that are most like V (lambda). Other methods of measuring spectral sensitivity seem more likely to depend on signals that travel through the parvocellular system.

Quantifying colour appearance. Part II. Testing colour models performance using lutchi colour appearance data

AbstractThe acquisition of the LUTCHI Colour Appearance Data has been described in Part I of this article. Having obtained the data, they were used to test the accuracy of prediction for various colour spaces and models. The results clearly indicate that Hunt's 91 model gives the best fit to the visual results of all the models studied. Hunt's 91 has been further refined to improve the fit to the colourfulness results, and this refined model has been designated Hunt‐ACAM (ACAM being the Alvey Colour Appearance Model). The error of prediction from Hunt‐ACAM is close to the typical error that is seen to occur between individuals' results and the mean visual results. This performance is considered to be very satisfactory, and the model is therefore believed to provide a reasonably accurate way of evaluating colour fidelity for various colour reproduction systems. Various chromatic‐adaptation transformations were also compared with three sets of corresponding chromaticities derived from the results of experiments conducted under four conditions of chromatic adaptation. The results are in reasonable agreement with those obtained by Helson et al. [Illum. Eng. 47, 221–233 (1952)] and Lam and Rigg [Ph.D. thesis, University of Bradford (1985)]. All results indicate that the Bradford and Hunt‐ACAM transformations perform the best and the second best, respectively, of all the selected formulae. The current CIE recommendation does not perform as well as expected.

Color appearance under conditions of chromatic adaptation and contrast

AbstractChromatic adaptation can significantly alter the color appearance of a light. We review measurements of changes in appearance caused by chromatic backgrounds and surrounds. Effects of long‐, middle‐ and short‐wavelength adapting lights are assessed by having observers adjust the physical light in a test patch to maintain a constant perceptual criterion: a test that appears neither reddish nor greenish. A variety of spatial and temporal stimulus configurations also is considered. An integrated account of the measurements is provided by the two‐process theory of chromatic adaptation, originally proposed by Hurvich and Jameson in 1958, which specifies an adapting light alters receptoral sensitivities and, simultaneously, contributes an additive increment to opponent chromatic responses.

The photoreceptors in atypical achromatopsia.

1. The receptoral mechanisms underlying the vision of two atypical achromats of the complete variety were studied with standard psychophysical procedures. 2. Under scotopic conditions the spectral sensitivity of each achromat was well described by the CIE (Commission Internationale de l'Eclairage) scotopic sensitivity function and the recovery of sensitivity after a retinal bleach showed characteristic duplex behaviour with the time constant of recovery of the slower phase matching that of normal rod vision for both foveal and peripheral stimulation. 3. Their spectral sensitivity was measured under conditions of chromatic adaptation in order to reveal any residual middle or long wavelength cone activity. Only one photopic spectral responses was found and this was adequately described by the spectral sensitivity function of Stiles pi 3 mechanism of normal vision. 4. Increment threshold measurements as a function of background intensity revealed a double-branched function in the fovea. The lower branch was found to have the spectral sensitivity of the rods; the upper branch that of Stiles' pi 3 mechanism. Stiles-Crawford measurements of directional sensitivity confirmed that the branch with the rhodopsin action spectrum had the directional sensitivity of rods and that the branch with the action spectrum of pi 3 had the directional sensitivity of cones. 5. These was no evidence for hue discrimination under photopic conditions. Regions of apparently normal performance on hue discrimination tests on more careful examination could be explained by luminosity judgements mediated by short wavelength-absorbing receptors. 6. We reject the notion of there being rhodopsin-filled cones in the fovea of these subjects. The foveal and peripheral vision of each of these achromats can be adequately described in terms of the participation of only two types of receptor, namely normally functional rods under scotopic conditions and normally functioning short wavelength-absorbing cones under photopic conditions. They are therefore functional blue mono-cone monochromats, an explanation which was originally proposed by Blackwell & Blackwell (1957) over thirty years ago.

Temporal properties of the short-wavelength cone mechanism: Comparison of receptor and postreceptor signals in the ground squirrel

Temporal properties of the short-wavelength cone mechanism of the California ground squirrel ( Spermophilus beecheyi), a dichromat, were explored with single light pulses and pulse trains. Both the electroretinogram (ERG) and the isolated PIII component of the retinal gross response were recorded under chromatic adaptation conditions that favored the detection of test lights by either the middle-wavelength mechanism or the short-wavelength mechanism. The ERG b -wave generated by the short-wavelength mechanism was significantly slower than that of the middle-wavelength mechanism, but there was no such difference in the PIII components of the two mechanisms. Analysis of PIII revealed that both cone types respond equally well to flicker at rates at least as high as 46 Hz. Differences in the temporal response properties of these two cone mechanisms must arise largely from post-receptoral interactions.

Spatial sensitization of the B cone pathways

Spatial sensitization functions were determined under chromatic adaptation conditions designed to isolate the short-wavelength-sensitive pathways (B cone pathways). Spatial sensitization occurs over large retinal dimensions for B cone detected targets and can be produced both by signals from B cones and by signals from R and/or G cones. Field sensitivity measures demonstrate that the mechanism producing sensitization on short-wavelength backgrounds has the spectral sensitivity of B cones. The field sensitivity on long-wavelength backgrounds does not correspond to any receptor spectral sensitivity or any π mechanism, but suggests that opponent interaction between medium and long-wavelength receptors produces sensitization of B cone detected targets.

Isolation of short-wavelength-sensitive cone photoreceptors in 4–6-week-old human infants

Spectral sensitivity was measured for nine infants, 4–6 weeks of age, and three adults under conditions of chromatic adaptation chosen to reveal the presence of short-wavelength-sensitive cones. Monochromatic test stimuli (400–550 nm) were presented at 2 Hz superimposed on a broadband, yellow background. Following 4 min of adaptation to the background, test stimuli were presented while recording the steady-state, visually-evoked cortical potential (VECP). Response averages were obtained for several radiance levels at each test wavelength, and the amplitude of the fundamental frequency was extracted from the digitized response with a fast-Fourier transform. These data were used to construct response vs intensity functions for each wavelength. A fixed criterion response was chosen from the latter family of functions to generate individual spectral sensitivity curves. These VECP spectral sensitivity functions matched the psychophysically-determined functions of adults, measured by the method of adjustment and with the same stimulus configuration. Peak sensitivity for infants and adults under these conditions occurred at about 440 nm, and the main lobe of the curve (400–500 nm) was well fitted by the Vos-Walraven short-wavelength cone fundamental. The only major difference between the infant and adult data was in the relative sensitivity of the secondary mode of the curves (above 500 nm). These results demonstrate the presence of short-wavelength-sensitive cones and a functional pathway to the visual cortex by 4–6 weeks of age.

Displacement thresholds for motion detection under conditions of chromatic adaptation

Abstract— The smallest, continuous target displacement which is sufficient to cause a sensation of movement was measured under conditions of chromatic adaptation. The experiments were carried out for test target and background field wavelengths which selectively isolate the activity of the colour mechanisms of the human eye. The results show that, when target detection is largely mediated by the red or green colour mechanism, a target displacement of 2–3′ in the foveal region is sufficient to cause a reliable sensation of movement. These displacement thresholds show only a small change as a function of target contrast or background retinal illuminance level. Similar results were obtained when the colour of the test target was the same as that of the background field (e.g. green, yellow or red), when no attempt was made to isolate a single colour mechanism. Test target and background wavelengths which isolate the activity of the blue colour mechanism yield displacement thresholds in the range 5–7′ and show a stronger dependence on target contrast and background retinal illuminance level. The experiments were repeated at several eccentricities and the results show that, for a test target and background field of the same colour and under conditions which isolate the green or red spectral response mechanism, the minimum target displacement required for motion detection appears to increase in a manner similar to the centre-width receptive-field size of broad-band, centre-surround transient neurons in the rhesus monkey retina [De Monasterio and Gouras (1975) J. Physiol., Lond.251, 167–195]. In contrast, displacement thresholds obtained under conditions which isolate the blue colour mechanism do not show significant variation for target presentation locations up to 25° of visual angle. These data relate well to other psychophysical results which reveal the spatial properties of motion-detecting mechanisms in human vision [Barbur and Ruddock (1980b) Biol. Cybernetics37, 93–98].