Rafael Huertas, Manuel Melgosa, and Enrique Hita, "Influence of random-dot textures on perception of suprathreshold color differences," J. Opt. Soc. Am. A 23, 2067-2076 (2006)
We have analyzed the way in which simulated textures made of random dots influence visual suprathreshold color tolerances. We considered 32 textures created by a systematic variation of the following variables: size, number, and color of the dots. Each texture was mapped on the five centers recommended by the International Commission on Illumination (CIE) in 1978 [Color Res. Appl. 3, 149 (1978)
]. A panel of five experienced observers determined the experimental tolerances using a CRT color monitor by the method of adjustment. At our observation distance, neither small differences in dot size (1 or ) nor sparse number of dots (less than 20% of the surface of the sample) changed the tolerances found for homogeneous samples. For the textures that led to statistically significant differences with respect to homogeneous samples, the parametric factors of CIEDE2000 and CIE94 color-difference formulas were fitted. These simulated textures consistently reduced the color difference perceived in a pair or, equivalently, increased the tolerances, mainly (but not only) lightness tolerance. The results demonstrate that it is not simple to provide a unique set of parametric factors for all the potential textures.
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The two sizes (1 or ) of the random dots are not considered. Color of the background sample is labeled with the subscript BS.
Types A, B, C, and D are termed relative textures.
Type E is termed absolute texture.
Table 4
Visual Tolerances for the Homogeneous Five CIE Centersa
Average tolerances for the observers with the standard deviation in parenthesis. For the achromatic center (gray), only lightness tolerances were considered. The last column corresponds to the average and standard deviation over centers.
Chroma tolerance with chroma correction (CIE94 units).
Hue tolerance with chroma correction (CIE94 units).
Table 5
Visual Tolerances for Textures with Statistically Significant Differences regarding Reference Tolerancesa
Tolerances averaged for sense of the tolerance, size of the dots, observers, and centers. Standard deviation in parenthesis.
Type and percentage of covered surface in parenthesis.
Table 6
Performance Factor PF/3 for Some of the Most Recent Color-Difference Formulas
Textures A (20%), A (50%), C (20%), C (50%), E (20%), E (50%), and E (80%).
Textures E (20%), E (50%), and E (80%).
Parametric factors fitted for each texture (shown in Fig. 5).
Leeds Colour Difference.
Tables (6)
Table 1
Color Coordinates of the Anchor Pair, Background, and Surrounda
Stimulus
Anchor pair
Sample 1
52.95±0.03
22.39±0.02
33.14±0.04
24.19±0.03
Sample 2
51.43±0.03
20.86±0.03
31.07±0.04
22.61±0.02
Surround
100.00±0.11
0.0±0.04
0.0±0.3
106.8±0.3
155.6±0.4
115.2±0.3
Background
54.42±0.02
0.19±0.18
23.93±0.01
35.12±0.04
25.767±0.012
Uncertainties were obtained from standard deviations of three independent measurements.
Table 2
Proposed and Measured Color Coordinates of the Five CIE 1978 Centers
The two sizes (1 or ) of the random dots are not considered. Color of the background sample is labeled with the subscript BS.
Types A, B, C, and D are termed relative textures.
Type E is termed absolute texture.
Table 4
Visual Tolerances for the Homogeneous Five CIE Centersa
Average tolerances for the observers with the standard deviation in parenthesis. For the achromatic center (gray), only lightness tolerances were considered. The last column corresponds to the average and standard deviation over centers.
Chroma tolerance with chroma correction (CIE94 units).
Hue tolerance with chroma correction (CIE94 units).
Table 5
Visual Tolerances for Textures with Statistically Significant Differences regarding Reference Tolerancesa
Tolerances averaged for sense of the tolerance, size of the dots, observers, and centers. Standard deviation in parenthesis.
Type and percentage of covered surface in parenthesis.
Table 6
Performance Factor PF/3 for Some of the Most Recent Color-Difference Formulas
Textures A (20%), A (50%), C (20%), C (50%), E (20%), E (50%), and E (80%).
Textures E (20%), E (50%), and E (80%).
Parametric factors fitted for each texture (shown in Fig. 5).
Leeds Colour Difference.