Effects of Light Wavelengths on the Performance of Color Absolute Judgments

2007 ◽  
Vol 364-366 ◽  
pp. 942-948
Author(s):  
Shih Miao Huang ◽  
Jui Chang Lin
Keyword(s):  
Standard Stimulus ◽  
Color Space ◽  
Judgment Task ◽  
Absolute Judgment ◽  
Just Noticeable Difference ◽  
Stimulus Color ◽  
Clockwise Direction ◽  
Color Differences ◽  
Comparison Of The Results ◽  
Color Judgment

Optically, humans can discriminate between colors as close as 2nm in wavelength in relative judgment task. However, there is little research to discuss color differences for absolute color judgments in which the comparison is held in memory. Therefore, the intent of this study was to explore effects of wavelengths on the Just Noticeable Difference (JND) of absolute judgments in our perceptual world. A color identification task was utilized to investigate the JND of wavelengths. In the experiment, the Standard Stimulus Color (SSC) and the Comparison Stimulus Color (CSC) were successively presented. The SSC which was presented first must be stored in working memory and recalled when the second color, CSC, is presented. Subjects had to decide if the CSC matched the SSC. Each CSC was presented four times for each subject in the experiment. The CSC wavelength that was recognized as different from the SSC twice was designed as a JND wavelength. Five SSC wavelengths with 100% saturation and 100% lightness were chosen from the hue circle of HLS color space which included 360 hues. Because the hue circle is a circle, the CSC may be on both sides of a SSC in the hue circle. The CSC hue which may be located on the clockwise direction or counter clockwise direction of the SSC was called clockwise direction color (CD) or counter clockwise direction color (CCD), respectively. The wavelengths expressed with HLS color space were translated into coordination of CIE1931 (x, y)-chromaticity diagram. The results indicated that threshold sensitivities varied for different wavelengths on absolute judgment tasks. The lights with longest or shortest wavelength had greater JNDs than ones with middle wavelengths for absolute judgment tasks. The comparison of the results of the experiment on absolute color judgment tasks and MacAdam’s (1942) findings for relative color judgment tasks were also discussed.

Method to Create Perceptually Uniform Color Gradients with Optimized Color Differences between each Step for Data Visualization

2020 ◽  
Vol 64 (1) ◽  
pp. 1634-1638
Author(s):  
Derek Millard ◽  
Bradley M. Davis ◽  
Samineh C. Gillmore
Keyword(s):  
Data Visualization ◽  
Color Space ◽  
Original Method ◽  
Visual Environment ◽  
Color Differences ◽  
Color Gradient ◽  
Color Gradients ◽  
Specific Implementation

This paper presents an original method to create optimized color differences between each step of a CIELAB perceptually uniform color gradient. The relevant equations for the necessary color space transformations are discussed, along with the procedure to determine and optimize the color differences between each gradient step. A specific implementation for perceptually uniform color gradients is discussed for safe terrain clearance in manned aviation during a degraded visual environment.

Hemispheric Asymmetry in Making Absolute Judgments of Monaurally Presented Pure Tones

1977 ◽  
Vol 44 (3) ◽  
pp. 923-928 ◽  
Author(s):  
Shripad G. Pendse
Keyword(s):  
Channel Capacity ◽  
Hemispheric Asymmetry ◽  
Judgment Task ◽  
Absolute Judgment ◽  
Pure Tones

Some recent studies have suggested that hemispheric asymmetry may be related to the quantity of information contained in a stimulus. To test this possibility, 20 subjects were given an auditory absolute-judgment task in which they were required to identify 3, 5, or 7 pure tones recorded on a tape. The presentation was monaural, and headphone placement was randomly alternated across subjects. The left ear showed a statistically significant advantage in identifying 5 tones and an insignificant advantage in identifying 3 or 7 tones. This result is discussed in terms of previous work on auditory channel-capacity and the desirability of using an absolute-judgment paradigm to study hemispheric asymmetry for other kinds of stimuli is indicated.

scholarly journals Apparent physical brightness of graphemes is altered by their synaesthetic colour in grapheme-colour synaesthetes

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Kyuto Uno ◽  
Kazuhiko Yokosawa
Keyword(s):  
Visual Processing ◽  
Standard Stimulus ◽  
Judgment Task ◽  
Neural Activation ◽  
Brightness Perception ◽  
Early Visual Processing ◽  
Colour Sensation ◽  
Colour Experience ◽  
Dark Colour ◽  
Mind's Eye

AbstractGrapheme-colour synaesthesia is a condition in which the visual perception of letters or numbers induces a specific colour sensation. In this study, we demonstrated that the apparent physical brightness of graphemes is modulated by the synaesthetic colours elicited by them. Synaesthetes first selected a synaesthetic colour corresponding to each capital letter and digit. Then, we selected a grapheme stimulus with a bright synaesthetic colour and one with a dark colour for each synaesthete. Finally, synaesthetes and non-synaesthete controls participated in a brightness judgment task, in which each participant judged the real brightness of each of the two stimuli compared to a standard stimulus. Compared to non-synaesthetes, synaesthetes judged a grapheme with a bright synaesthetic colour to be brighter than one with a dark synaesthetic colour, suggesting that the synaesthetic colour experience of synaesthetes alters their brightness perception. Such alteration in real brightness perception was observed both in those who experienced synaesthetic colours in external space (projector-type synaesthetes) and in those who experienced such colours ‘in the mind’s eye’ (associator-type synaesthetes). These results support the view that early visual processing is modulated by feedback transmitted from the V4 colour area, the neural activation of which accompanies synaesthetic colour experience.

Subjective Sensation of Color Differences – Determination of Thresholds Depending on Color Tones and Resolution

2015 ◽  
Vol 21 (1) ◽  
pp. 21-27 ◽  
Author(s):  
Christian Brischke ◽  
Tanja Borcharding ◽  
Uta Mengel
Keyword(s):  
Color Space ◽  
Color Difference ◽  
Threshold Values ◽  
Color Tone ◽  
Color Changes ◽  
Art Objects ◽  
Color Differences ◽  
Subjective Sensation ◽  
Total Color Difference

Abstract Colors are frequently defined by three points on the L*a*b* coordinates of the CIELAB color space, and the distance between two colors can be expressed as the total color difference ΔE. In particular with respect to reproducibility of print media color differences are an important parameter, as well as for car finishes and textile dyes. Color changes are also the result of ageing and weathering which is an issue for art objects and in the building and restoration sector. However, the subjective perceptibility of color differences depends on numerous factors and general thresholds are difficult to define. This study aimed therefore on defining tolerance levels for color changes in dependence of color tones and color tone combinations as well as their resolution. In total 30 test persons evaluated samples, which had been painted with acrylic artist colors with defined color differences (ΔE = 0–7). The test subjects realized color differences already at ΔE = 1–4 for the highest resolution. Threshold values have been identified for different tones as well as the effect of interdependencies between tones and the level of color heterogeneity between adjacent areas.

Fundamental Comparison of Image Quality Metrics

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 81-81
Author(s):  
P G J Barten
Keyword(s):  
Image Quality ◽  
Spatial Frequency ◽  
Imaging System ◽  
Quality Metrics ◽  
Sensitivity Function ◽  
Just Noticeable Difference ◽  
Modulation Transfer ◽  
Image Quality Metrics ◽  
Comparison Of The Results ◽  
The Right

In most image quality metrics (eg MTFA, ICS, SQF, DDD, SQRI) use is made of the modulation transfer function (MTF) of the imaging system and the contrast sensitivity function (CSF) of the human visual system. All metrics usually show a positive correlation with perceived image quality. This does not, however, say much about the correctness of the underlying equations. Defocusing experiments where an image is defocused by one just-noticeable difference can give information about the contribution of different spatial-frequency ranges to image quality. By performing defocusing experiments with images where contrast is also varied, information can be obtained about the dependence of image quality on contrast. In our investigation defocusing measurements from Baldwin (1940), Carlson and Cohen (1980) and Watt and Morgan (1983) were used. Comparison of the results with the fundamental dependence of some image quality metrics on spatial frequency and contrast indicates that only the SQRI (square-root integral) showed the right behaviour with respect to these parameters.

Effect of a Mid-Series Anchor on Absolute Judgments of Duration by Schizophrenics, Neurologically Impaired, and Normals

1975 ◽  
Vol 40 (2) ◽  
pp. 671-677 ◽  
Author(s):  
Susan A. Locke
Keyword(s):  
Information Transmission ◽  
Interstimulus Interval ◽  
Judgment Task ◽  
Absolute Judgment ◽  
Auditory Stimuli ◽  
Experimental Task ◽  
Neurologically Impaired ◽  
The Absolute

36 normal, 36 schizophrenic, and 36 neurologically impaired Ss were compared for their ability to temporally discriminate brief auditory stimuli. The experimental task was the absolute judgment of 3, 5, or 9 stimuli ranging in duration from 0.10 to 1.90 sec. Half of the Ss in each group were “assisted” by the presentation of a repeated mid-series anchor. The interval between the presentation of the anchor and the variable stimuli was varied. With the addition of a mid-series anchor, normal Ss demonstrated an increase in information transmission and a decrease in response stereotypy; schizophrenics demonstrated a slight decrease in information transmission and a slight increase in response stereotypy; neurologically impaired Ss were essentially unaffected. Changes in interstimulus interval on the anchored judgment task did not influence information transmission.

Relationship Between Color Discrimination and Neural Responses in the Inferior Temporal Cortex of the Monkey

2008 ◽  
Vol 100 (6) ◽  
pp. 3361-3374 ◽  
Author(s):  
Takehiro Matsumora ◽  
Kowa Koida ◽  
Hidehiko Komatsu
Keyword(s):  
Anterior Part ◽  
Large Population ◽  
Temporal Cortex ◽  
Quantitative Relationship ◽  
Color Discrimination ◽  
Judgment Task ◽  
Inferior Temporal Cortex ◽  
Operating Characteristics ◽  
Behavioral Threshold ◽  
Color Judgment

Earlier studies suggest that the inferior temporal (IT) cortex of the monkey plays a key role in color discrimination. Here, we examined the quantitative relationship between color judgment in monkeys and the responses of color-selective neurons in the anterior part of the IT cortex (area TE) by comparing neuronal activity and behavior recorded simultaneously while the monkeys performed a color-judgment task. We first compared the abilities of single neurons and monkeys to discriminate color. To calculate a neuron's ability to discriminate color, we computed a neurometric function using receiver-operating-characteristics analysis. We then compared the neural and behavioral thresholds for color discrimination and found that, in general, the neural threshold was higher than the behavioral threshold, although occasionally the reverse was true. Variation in the neural threshold across the color space corresponded well with that of the behavioral threshold. We then calculated the choice probability (CP), which is a measure of the correlation between the trial-to-trial fluctuations in neuronal responses and the monkeys' color judgment. On average, CPs were slightly but significantly greater than 0.5, indicating the activities of these TE neurons correlate positively with the monkeys' color judgment. This suggests that individual color-selective TE neurons only weakly contribute to color discrimination and that a large population of color-selective TE neurons contribute to the performance of color discrimination.

scholarly journals The Efficacy of Linked Color Imaging in the Endoscopic Diagnosis of Barrett’s Esophagus and Esophageal Adenocarcinoma

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Mamoru Tokunaga ◽  
Tomoaki Matsumura ◽  
Kentaro Ishikawa ◽  
Tatsuya Kaneko ◽  
Hirotaka Oura ◽  
...  
Keyword(s):  
Barrett’S Esophagus ◽  
Esophageal Adenocarcinoma ◽  
Barrett's Esophagus ◽  
Color Space ◽  
Color Difference ◽  
Blue Laser ◽  
Color Imaging ◽  
Color Differences ◽  
Blue Laser Imaging ◽  
Linked Color Imaging

Background. The present study aimed to evaluate the efficacy of linked color imaging (LCI) in diagnosing Barrett’s esophagus (BE) and esophageal adenocarcinoma (EAC). Methods. A total of 112 and 12 consecutive patients with BE and EAC were analyzed. The visibility scores of BE and EAC ranging from 4 (excellent visibility) to 0 (not detectable) were evaluated by three trainees and three experts using white light imaging (WLI), LCI mode, and blue laser imaging bright (BLI-b) mode. In addition, L ∗ a ∗ b ∗ color values and color differences ( Δ E ∗ ) were evaluated using the CIELAB color space system. Results. The visibility score of the BE in LCI mode ( 2.94 ± 1.32 ) was significantly higher than those in WLI ( 2.46 ± 1.48 ) and BLI-b mode ( 2.35 ± 1.46 ) ( p < 0.01 ). The color difference ( Δ E ∗ ) from the adjacent gastric mucosa in LCI mode ( 17.11 ± 8.53 ) was significantly higher than those in other modes ( 12.52 ± 9.37 in WLI and 11.96 ± 6.59 in BLI-b mode, p < 0.01 ). The visibility scores of EAC in LCI mode ( 2.56 ± 1.47 ) and BLI-b mode ( 2.51 ± 1.28 ) were significantly higher than that in WLI ( 1.64 ± 1.46 ) ( p < 0.01 ). The color difference ( Δ E ∗ ) from the adjacent normal Barrett’s mucosa in LCI mode ( 19.96 ± 7.97 ) was significantly higher than that in WLI ( 12.95 ± 11.86 ) ( p = 0.03 ). Conclusion. The present findings suggest that LCI increases the visibility of BE and EAC and contributes to the improvement of the detection of these lesions.

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