Heterochromatic Brightness Matching Research Articles

Heterochromatic brightness matching experiments to evaluate brightness prediction model including Helmholtz-Kohlrausch effect

In this study, the brightness matching experiment was conducted to obtain the equivalent luminance between chromatic and achromatic colors. Observers adjusted the luminance of achromatic colors until achromatic colors were perceived as having the same brightness with chromatic colors. A total of 285 chromatic colors having three different luminance levels, 30cd/m^2, 95cd/m^2, and 300cd/m^2 were used as the test colors. Twenty observers participated in this experiment repeating three times. The results showed that the brightness-to-luminance (B/L) ratio, where brightness means the luminance of achromatic color, increases as CIE 1976 saturation increases in all luminance levels indicating the Helmholtz-Kohlrausch effect. Also, as the luminance level of chromatic color increases, B/L ratio decreases. It is found that the existing color appearance models predicting the H-K effect overestimate the brightness increment by chroma compared to our new heterochromatic brightness matching data set.

Equivalent lightness of elderlies investigated by cataract experiencing goggles

People get cataract in their eyes when they age. The color perceived by the senile cataract eyes desaturates because of the environment light that scatters in the eyes by the hazy crystalline lenses. We investigated the effect of the desaturation on brightness of objects in terms of the equivalent lightness , which is composed of the achromatic lightness and the chromatic lightness . If the color desaturates, becomes smaller and consequently becomes smaller in the cataract eyes. with and without cataract experiencing goggles at room illuminances to cover mesopic to photopic level was measured. Red, yellow, green, and blue patches of size 2° × 2° arc of the visual angle were investigated with the direct heterochromatic brightness matching between the color patches and a gray scale. Both took about the same value. with goggles was then transferred to the final where the matching gray scale was observed without goggles to express the equivalent lightness of cataract eyes by the gray scale perceived by normal eyes. with goggles was lower than without goggles by about 10 L* units in all the four colors. This reduction was almost equal to the reduction of L* by the reduced transmittance of the goggles showing that there was no effect of color desaturation. The color appearance in the color patches was measured by the elementary color naming method, and the results clearly showed the color desaturation with goggles implying decrease of . We concluded that the scattered environment light compensated the decrease of to keep the brightness of stimuli unchanged. © 2011 Wiley Periodicals, Inc. Col Res Appl, 38, 267–276, 2013

Evaluation of discomfort glare from color leds and its correlation with individual variations in brightness sensitivity

AbstractThe light‐emitting diode (LED) has attracted attention as an alternative light source to fluorescent and incandescent lighting. The characteristics of LED light are different from other sources, but regulations for LED products have not been completely established. Common LED lights, such as automotive lamps, street lighting systems and traffic lights, are produced under the existing glare regulations for other light sources, and some organizations are seeking to establish standardized regulations for LED products. Glare can impair vision and cause discomfort and must be considered when establishing regulations for lights. In this study, we measured the sensitivity of observers to the discomfort glare from color LEDs and analyzed the correlation between discomfort glare sensitivity and brightness sensitivity using heterochromatic brightness matching and flicker photometry. The results indicate a correlation between discomfort glare sensitivity and brightness sensitivity using blue LEDs and mild correlations with green and red LEDs. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2010.

Guest Editorial: Shedding new light on the twilight zone

Guest Editorial: Shedding new light on the twilight zone

Induction effects for heterochromatic brightness matching, heterochromatic flicker photometry, and minimally distinct border: implications for the neural mechanisms underlying induction

Brightness induction refers to the finding that the apparent brightness of a stimulus changes when surrounded by a black versus a white stimulus. In the current study, we investigated the effects of black/white surrounding stimuli on settings made between red and green stimuli on three different tasks: heterochromatic brightness matching (HBM), heterochromatic flicker photometry (HFP), and minimally distinct border (MDB). For HBM, subjects varied the relative luminance between the red and green stimuli so that the brightness of the two colors appeared equal. For the two other tasks, matches were made based on minimizing red/green flicker (HFP) or the saliency of a red/green border (MDB). For all three tasks, the presence of black/white surrounding stimuli significantly altered red/green settings, demonstrating the existence of induction effects. These results are discussed in terms of which underlying color pathways (L+ M versus L-M) may contribute to induction effects for the different tasks.

Centering biases in heterochromatic brightness matching

When the method of constant stimuli is used to measure heterochromatic brightness matches, the resulting matches can be strongly biased toward the center of the range of test luminances used [Teller, D. Y., Pereverzeva, M., & Civan, A. L. (2003). Adult brightness vs. luminance as models of infant photometry: variability, biasability, and spectral characteristics for two age groups favor the luminance model. Journal of Vision, 3, 333–346]. In the present paper, we investigate the source of this centering bias. The stimuli were 2° red squares presented in a gray surround. In the main experiments, two ranges of stimulus luminance were presented in separate physical locations on a video monitor, but with test trials interleaved in time. Subjects either fixated a fixation cross (fixation condition), creating different retinotopic locations for the two luminance ranges, or foveated each stimulus as it appeared (foveation condition), creating identical retinotopic locations for both ranges. In the fixation condition, the two different stimulus sets resulted in a simultaneous centering bias—two different brightness matches at two different retinotopic locations at the same time. This effect was essentially eliminated in the foveation condition. A dichoptic foveation condition also revealed no centering bias. The results suggest that under the conditions tested, the centering bias is caused by a process located at a post-retinal but still retinotopically organized level of the visual system, rather than by either a retinal process or a more central, spatiotopically organized one.

Mesopic models—from brightness matching to visual performance in night-time driving: a review

At present, suitable methods to evaluate the visual effectiveness of lighting products in the mesopic region are not available. The majority of spectral luminous efficiency functions obtained to date in the mesopic range have been acquired by heterochromatic brightness matching. However, the most recent studies in the mesopic field have adopted a task performance-based approach. This paper summarizes the major mesopic models proposed so far, presenting in detail the experimental conditions of these studies. The authors represent a research consortium which has adopted the task performance-based approach for night-time driving in which mesopic visual performance has been divided into three subtasks. Data for each sub-task will be generated by using a set of common parameter values and 120 observers. The approach and methods used by the consortium are presented.

Centering biases in heterochromatic brightness matching

Abstract When the method of constant stimuli is used to measure heterochromatic brightness matches, the resulting matches can be strongly biased toward the center of the range of test luminances used [Teller, D. Y., Pereverzeva, M., & Civan, A. L. (2003). Adult brightness vs. luminance as models of infant photometry: variability, biasability, and spectral characteristics for two age groups favor the luminance model. Journal of Vision , 3, 333–346]. In the present paper, we investigate the source of this centering bias. The stimuli were 2° red squares presented in a gray surround. In the main experiments, two ranges of stimulus luminance were presented in separate physical locations on a video monitor, but with test trials interleaved in time. Subjects either fixated a fixation cross (fixation condition), creating different retinotopic locations for the two luminance ranges, or foveated each stimulus as it appeared (foveation condition), creating identical retinotopic locations for both ranges. In the fixation condition, the two different stimulus sets resulted in a simultaneous centering bias—two different brightness matches at two different retinotopic locations at the same time. This effect was essentially eliminated in the foveation condition. A dichoptic foveation condition also revealed no centering bias. The results suggest that under the conditions tested, the centering bias is caused by a process located at a post-retinal but still retinotopically organized level of the visual system, rather than by either a retinal process or a more central, spatiotopically organized one.

Adult brightness vs. luminance as models of infant photometry: variability, biasability, and spectral characteristics for the two age groups favor the luminance model.

When infants fail to make chromatic discriminations, do the characteristics of their performance minima coincide more closely with the properties of adult luminance matches or heterochromatic brightness matches? In addition to their spectral properties, adult luminance matches are typically characterized by relatively small individual differences, whereas brightness matches are believed to be both more variable and more biasable. Two complementary experiments were carried out on adults and 8-week-old infant subjects. Both groups were tested with small (1.5 degrees to 4 degrees ) red and blue test fields of varying luminances, embedded in a white surround. In adults, heterochromatic brightness matches were measured. Individual differences spanned about 0.5 log units, and brightness matches could be biased by as much as 0.8 log units by varying the range of test field luminances. In infants, the locations of performance minima were measured. Individual differences spanned less than 0.1 log units, the mean performance minima coincided with predictions based on V10(lambda), and the location of the performance minimum was nearly unaffected by the range of test field luminances used. Thus by all three criteria, these data suggest that infants' performance minima are mediated by luminance rather than by brightness signals. To date there remains no evidence that the infant visual system computes a brightness signal.

加齢による水晶体黄変が色覚におよぼす効果

We conducted four kinds of psychophysical measurements on color vision to investigate whether the change in lens spectral transmittance that comes with aging is the primary factor in the change in color vision. We asked two observers (22 and 24 years old) to adapt to the scene while wearing goggles equipped with filters that simulate spectral transmittance at the retinal level of a person of 80 years old, when worn by 20 years old observer. During the test, which lasted as long as 12 hours, the observers performed (1) unique-white setting, (2) heterochromatic flicker photometry (HFP), (3) heterochromatic brightness matching (HBM), and (4) 100-hue test. The change in the results with and without the goggle showed that only difference in HFP sensitivity coincided exactly with the filter transmittance. A similar tendency was found in the difference between 20 and 80year-old observers in a previous study. The other tests matched with neither the difference in spectral transmittance nor the difference between 20-and 80year-old experimental results. Our results suggest that neural circuits, which may differ from those for illuminant change, play a significant role in correcting the relative spectrum change on the retina.

Brightness induction in a chromatic center?achromatic surround configuration

The brightness changes induced in red and green tests by an achromatic surround were studied using a nulling method. The amplitude of the nulling modulation was found to increase approximately linearly with the temporal contrast of an inducing field of constant average luminance. The amplitude of the nulling modulation relative to the amplitude of the inducing modulation increased with increasing test luminance and decreased with increasing mean luminance of the surround. For a given contrast, the amplitude of the nulling modulation increased with the amplitude of the inducing modulation. Nevertheless, the amplitude of the nulling modulation was comparatively larger when the mean luminance of the surround was close to the test luminance. These results were fit by the model developed by Spehar et al. [Vision Res. 36 (1996)]. In this model, the total brightness induced by a surround is given by a weighted spatial summation of the induced effects from each point in the surround with local luminance gain controls in the test and surround fields. It is assumed that the magnitude of induction from each surround element is gain controlled by the difference between the mean luminance of the test and the individual surround elements. The values of the nulling modulation were practically the same for the green and the red test. On the contrary, with a heterochromatic brightness matching method, the luminance changes needed to match the test brightness depended on test chromaticity. At equal surround luminance, the largest changes in luminance were for the green test and the smallest were for the blue test, the red test being at an intermediate level. The influence of the test chromaticity in the direct heterochromatic brightness matching experiment shows a contribution of the chromatic channel. The modulation nulling conceals this contribution, because the task performed by the observer seems to involve the achromatic channel only. © 1997 John Wiley & Sons, Inc. Col Res Appl, 22, 228–239, 1997.

Influence of luminance flicker and purity on heterochromatic brightness matching and hue discrimination: a postreceptoral opponent process.

We have studied psychophysically the characteristics of the postreceptoral stage of visual processing, using heterochromatic brightness matching (HBM) between 540 and 600 nm, and hue discrimination between 565 and 585 nm, under differing luminance flicker (0-30 Hz) and excitation purity (1.0-0.1) conditions. The HBM curves exhibit deeper minima around 575 nm with decreasing purity. The minimum is generally most pronounced with a 3 Hz flicker and least pronounced with a 30 Hz flicker. Hue discrimination ability is relatively insensitive to flicker and deteriorates at the lower purities. The HBM results for low purities can be explained by the upper envelope of activities in PC- and MC-pathways.

L and M cone input into spectral sensitivity functions: a reanalysis.

In order to better understand the nature of long-wavelength (L) and middle-wavelength (M) cone input into spectral sensitivity functions and determine the reliability with which it is possible to predict L:M cone inputs, we developed analytical methods to determine confidence intervals for L:M cone input for spectral sensitivity functions or data transformed to cone-contrast space. Spectral sensitivity functions measured by direct heterochromatic brightness matches are dominated by the L/M opponent channel over most of the spectral range. For detection of large/ long test stimuli, spectral sensitivity functions show a characteristic "notch" at the adapting wavelength, with the L/M opponent channel dominating most of the spectral range. Flicker increment threshold (FIT) spectral sensitivity functions display many of the characteristics of the luminance flicker mechanism described by Stromeyer et al. (1987). [Vision Research, 27, 1113-1137]. Previous modelling of FIT spectral sensitivity functions proposed a 2:1 L:M cone input for most of testing conditions. We show that FIT spectral sensitivity functions are dominated by L cones but show L cone suppression under bright red adapting fields. For the fitted spectral sensitivity functions or simulated data sets, we found small confidence intervals for L:M cone input into the L/M opponent channel and conclude that it is possible to reliably predict L:M cone input ratios. However, for similar data sets of additive spectral sensitivity functions, we found large confidence intervals for L:M cone input ratios and conclude that it is not possible reliably predict L:M cone input into the L/M non-opponent channel using available spectral sensitivity functions.

明るさの分光視感効率と視力

In order to investigate the effect of visual acuity on the luminous efficiency function determined by heterochromatic brightness matching (HBM), the spectral luminous efficiency function and visual acuity were measured for 15 observers including 8 high-acuity and 7 low-acuity observers under three artificially corrected conditions: high acuity, low acuity and no correction. It was found that the shape of the spectral luminous efficiency function did not differ between the two groups with high-acuity and low-acuity nor among the three artificially corrected acuity conditions. These findings were confirmed by principal component analysis of the data. It is concluded that it is difficult to classify the type of luminous efficiency function for brightness by considering the visual acuity of an observer.

Spectral efficiency across the life span: flicker photometry and brightness matching.

Spectral efficiency functions were measured for 50 color-normal observers (aged 19-85 years) by means of heterochromatic flicker photometry (HFP) and heterochromatic brightness matching (HBM). Foveally viewed, circular, 1.2 degrees-diameter stimuli were presented as 3-s flashes (50% duty cycle) in Maxwellian view. Monochromatic lights (420-700 nm; 16 wavelengths) were equated to a 100-Td (trolands), broadband white standard in both procedures. In both HFP and HBM, average sensitivity (specified at the cornea) decreased at short wavelengths with increasing age, consistent with age-related increases in the density of the ocular media. The short-wavelength HBM decline was of lower magnitude than the HFP decline. HFP data were modeled by a weighted additive combination of long- and middle-wavelength-cone inputs and density spectra of the ocular media and macular pigment. HBM data were analyzed with an upper envelope of additive and subtractive combinations of log-transformed cone absorption functions. These analyses indicated that HBM sensitivity, specified at the retina by correction for estimated lens and macular pigment density, increased with age in an approximately wavelength-independent manner over a broad range from 420 to 560 nm.

Brightness matching and colour discrimination in young diabetics without retinopathy

This study used the methods of the Farnsworth-Munsell 100-hue test (FM-100), heterochromatic brightness matching (HBM) and wavelength discrimination to test the sensitivity and colour vision of 20 juvenile diabetics with no (16) or very mild (4) retinopathy. Their results were compared to an age-matched control group. The FM-100 results showed a significant increase in error scores throughout the spectrum in comparison to the controls. This deterioration in colour vision was confirmed in the results for the wavelength discrimination task, tested between 440 and 640 nm, where the just noticeable difference in colour was, in general, larger for the diabetic group than the control group. Only at 460 nm were the results of the diabetics similar to those of the controls. The diabetic group were also less sensitive than the control group in the HBM task between 480 and 600 nm. The results show that a deficit in sensitivity and colour vision occurs in diabetics before the onset of a clinically visible retinopathy.

Individual differences of the contribution of chromatic channels to brightness.

Perceived brightness is considered to be a combined consequence of outputs of the luminance channel and the chromatic channels in the visual system. The differences of logarithmic spectral luminous efficiencies between heterochromatic brightness matching and flicker photometry that were obtained from 16 subjects were examined by using principal component analysis. The luminous-efficiency difference between the two methods is described by only two principal components. Individual characteristics of the contribution of chromatic channels to brightness can be specified by measuring luminous efficiencies at 470 and 660 nm.

Specification of individual variation in luminous efficiency for brightness

Principal component analysis was applied to spectral luminous efficiencies determined by the heterochromatic brightness matching by 51 and 70 observers for the field size. 2° and 10°, respectively, which were used to derive the CIE Vb,2(Λ) and Vb,10(Λ). Four principal components were found to explain the individual variation. the two deviation indices were introduced by slightly modifying the first and second principal scores and they were effectively used to specify individual variations and to predict the spectral luminous efficiency curve. Equations were derived to predict these two deviation indices as functions of luminous efficiencies at two wavelengths, 460 and 640 nm in the case of 2° field and 470 and 630 mm in 10° field. the luminous efficiency curves thus predicted by the two deviation indices fitted very nicely to the experimentally determined luminous efficiency curves of all the observers. A way to utilize the deviation indices in practice where observers play an important role is proposed to avoid some confusion that may take place because of individual variation.

照度レベルによる色の見えの等価明度への寄与

To investigate the relationship between the equivalent lightness and the color appearance of colored objects, 39 colored chips were used as stimuli to measure the equivalent lightness and the three attributes of whiteness, blackness and chromaticness at illuminance levels from 0.01 to 3000 lx. The first method, which has already been reported by the authors, is the determination of the equivalent lightness of colored objects by using heterochromatic brightness matching. In this paper, the color appearance of a colored object was measured by the values of its whiteness, blackness and chromaticness. It was observed that the whiteness corresponding to illuminance is directly related to the theoretical achromatic lightness, and the chromaticness corresponding to illuminance is also directly related to chromatic lightness. Consequently, the equivalent lightness corresponding to illuminance can be explained by adding the chromaticness to the whiteness.

Equivalent lightness of colored objects of equal munsell chroma and of equal munsell value at various illuminances

AbstractEquivalent lightness was determined for 26 colored surfaces by heterochromatic brightness matching with a grey scale. The illuminance for observation was varied from 0.01 to 1000 lx to cover scotopic, mesopic, and photopic vision, and the equivalent lightness‐versus‐log illuminance curve was obtained for every stimulus. The shape of the curves did not change if the surfaces had the same Munsell hue and chroma. It differed significantly if they had different hues or different chroma. The curves were interpreted in terms of achromatic lightness and chromatic lightness, which are both subject to change with illuminance level. The achromatic lightness was assumed to follow the Purkinje shift and the chromatic lightness monotonically increased with illuminance. The chromatic lightness was larger for larger Munsell chroma within a single hue.