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Contribution of a luminance-dependent S-cone mechanism to non-assimilative color spreading in the watercolor configuration.

Kimura E, Kuroki M - Front Hum Neurosci (2014)

Bottom Line: When the luminance condition was reversed and the IC contrast was greater than the OC contrast (lower IC luminance condition), the color spreading was non-assimilative and yellowish.When the color spreading was analyzed in terms of cone-opponent excitations, the results were consistent with the interpretation that the color spreading is explainable by a combination of chromatic diffusion from the IC and chromatically opponent induction from the OC.These findings provided several constraints on possible visual mechanisms underlying the watercolor effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Faculty of Letters, Chiba University Chiba-shi, Japan.

ABSTRACT
In the watercolor configuration composed of wavy double contours, both assimilative and non-assimilative color spreading have been demonstrated depending on the luminance conditions of the inner and outer contours (IC and OC, respectively). This study investigated how the induced color in the watercolor configuration was modulated by combinations of the IC and the OC color, particularly addressing non-assimilative color spreading. In two experiments, the IC color was fixed to a certain color and combined with various colors selected from a hue circle centered at the background white color. Color spreading was quantified with a chromatic cancelation technique. Results showed that both the magnitude and the apparent hue of the color spreading were largely changed with the luminance condition. When the IC contrast (Weber contrast of the IC to the background luminance) was smaller in size than the OC contrast (higher IC luminance condition), the color spreading was assimilative. When the luminance condition was reversed and the IC contrast was greater than the OC contrast (lower IC luminance condition), the color spreading was non-assimilative and yellowish. When the color spreading was analyzed in terms of cone-opponent excitations, the results were consistent with the interpretation that the color spreading is explainable by a combination of chromatic diffusion from the IC and chromatically opponent induction from the OC. The color spreading in the higher IC luminance condition mainly reflected the chromatic diffusion by both (L-M) and S cone-opponent mechanisms. The non-assimilative color spreading in the lower IC luminance condition mostly reflected S-cone mediated opponent induction and the contribution of -S inducing mechanisms was differentially large. These findings provided several constraints on possible visual mechanisms underlying the watercolor effect.

No MeSH data available.


Chromatic cancelation data of Experiment 1 shown in the CIE u′v′ chromaticity diagram. Different symbols designate the mean chromaticity coordinates necessary to cancel the induced color. Left and right panels respectively show results obtained in the higher IC luminance condition and those in the lower IC luminance condition. Top, middle, and bottom panels respectively show results in the red IC, orange IC, and achromatic IC conditions. Correspondence between the OC color and colored symbols was presented graphically in Figure 2. Table 1 listed the azimuth of the OC color in the CIE u′v′ chromaticity diagram and the relative color angle between the IC and the OC. The legends in the figure designate the azimuth of the OC color. Error bars show ±1 SEM across observers. Other aspects are the same as those shown in Figure 2.
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Figure 4: Chromatic cancelation data of Experiment 1 shown in the CIE u′v′ chromaticity diagram. Different symbols designate the mean chromaticity coordinates necessary to cancel the induced color. Left and right panels respectively show results obtained in the higher IC luminance condition and those in the lower IC luminance condition. Top, middle, and bottom panels respectively show results in the red IC, orange IC, and achromatic IC conditions. Correspondence between the OC color and colored symbols was presented graphically in Figure 2. Table 1 listed the azimuth of the OC color in the CIE u′v′ chromaticity diagram and the relative color angle between the IC and the OC. The legends in the figure designate the azimuth of the OC color. Error bars show ±1 SEM across observers. Other aspects are the same as those shown in Figure 2.

Mentions: The cancelation settings averaged across different observers are shown in the CIE u′v′ chromaticity diagram (Figure 4). As expected, different patterns of results were found in the higher and the lower IC luminance condition. The effects of the OC color were less in the higher IC color condition (left panels), but they were greater in the lower IC luminance condition (right panels). However, the results also deviated from the expectation. In the higher IC luminance condition (Figure 4, left), when the IC color was red (top left panel) or orange (middle left panel), the cancelation settings are located closely on the dotted line representing the complementary color of the IC. This result indicates that the induced color was mostly determined by the IC color. However, the OC color also appears to affect the induced color. Particularly, the cancelation settings represented by magenta inverted triangles, red squares, and purple circles deviated to the −v′ (counterclockwise) direction, which indicates that the induced color was yellower than the IC color. When the IC was achromatic, color spreading from the IC was not expected. However, the cancelation settings were shifted slightly to the +S/(L+M) (downward) direction, which reflects yellow spreading. In the lower IC luminance condition (Figure 4, right), the pattern of the results was somehow similar to that depicted in Figure 3C. However, the color spreading was much stronger in a yellow direction [i.e., +S/(L+M) direction], particularly for the cancelation settings represented by magenta inverted triangles, red squares, and purple circles. In general, these results are consistent with the findings by Kimura and Kuroki (2014), showing that assimilative color spreading was stronger when the IC contrast (the Weber contrast of the IC to the background luminance) was smaller than the OC contrast, whereas non-assimilative yellow spreading was stronger when the IC contrast was greater than the OC contrast. However, more detailed analysis of the induced color is necessary.


Contribution of a luminance-dependent S-cone mechanism to non-assimilative color spreading in the watercolor configuration.

Kimura E, Kuroki M - Front Hum Neurosci (2014)

Chromatic cancelation data of Experiment 1 shown in the CIE u′v′ chromaticity diagram. Different symbols designate the mean chromaticity coordinates necessary to cancel the induced color. Left and right panels respectively show results obtained in the higher IC luminance condition and those in the lower IC luminance condition. Top, middle, and bottom panels respectively show results in the red IC, orange IC, and achromatic IC conditions. Correspondence between the OC color and colored symbols was presented graphically in Figure 2. Table 1 listed the azimuth of the OC color in the CIE u′v′ chromaticity diagram and the relative color angle between the IC and the OC. The legends in the figure designate the azimuth of the OC color. Error bars show ±1 SEM across observers. Other aspects are the same as those shown in Figure 2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4260510&req=5

Figure 4: Chromatic cancelation data of Experiment 1 shown in the CIE u′v′ chromaticity diagram. Different symbols designate the mean chromaticity coordinates necessary to cancel the induced color. Left and right panels respectively show results obtained in the higher IC luminance condition and those in the lower IC luminance condition. Top, middle, and bottom panels respectively show results in the red IC, orange IC, and achromatic IC conditions. Correspondence between the OC color and colored symbols was presented graphically in Figure 2. Table 1 listed the azimuth of the OC color in the CIE u′v′ chromaticity diagram and the relative color angle between the IC and the OC. The legends in the figure designate the azimuth of the OC color. Error bars show ±1 SEM across observers. Other aspects are the same as those shown in Figure 2.
Mentions: The cancelation settings averaged across different observers are shown in the CIE u′v′ chromaticity diagram (Figure 4). As expected, different patterns of results were found in the higher and the lower IC luminance condition. The effects of the OC color were less in the higher IC color condition (left panels), but they were greater in the lower IC luminance condition (right panels). However, the results also deviated from the expectation. In the higher IC luminance condition (Figure 4, left), when the IC color was red (top left panel) or orange (middle left panel), the cancelation settings are located closely on the dotted line representing the complementary color of the IC. This result indicates that the induced color was mostly determined by the IC color. However, the OC color also appears to affect the induced color. Particularly, the cancelation settings represented by magenta inverted triangles, red squares, and purple circles deviated to the −v′ (counterclockwise) direction, which indicates that the induced color was yellower than the IC color. When the IC was achromatic, color spreading from the IC was not expected. However, the cancelation settings were shifted slightly to the +S/(L+M) (downward) direction, which reflects yellow spreading. In the lower IC luminance condition (Figure 4, right), the pattern of the results was somehow similar to that depicted in Figure 3C. However, the color spreading was much stronger in a yellow direction [i.e., +S/(L+M) direction], particularly for the cancelation settings represented by magenta inverted triangles, red squares, and purple circles. In general, these results are consistent with the findings by Kimura and Kuroki (2014), showing that assimilative color spreading was stronger when the IC contrast (the Weber contrast of the IC to the background luminance) was smaller than the OC contrast, whereas non-assimilative yellow spreading was stronger when the IC contrast was greater than the OC contrast. However, more detailed analysis of the induced color is necessary.

Bottom Line: When the luminance condition was reversed and the IC contrast was greater than the OC contrast (lower IC luminance condition), the color spreading was non-assimilative and yellowish.When the color spreading was analyzed in terms of cone-opponent excitations, the results were consistent with the interpretation that the color spreading is explainable by a combination of chromatic diffusion from the IC and chromatically opponent induction from the OC.These findings provided several constraints on possible visual mechanisms underlying the watercolor effect.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Faculty of Letters, Chiba University Chiba-shi, Japan.

ABSTRACT
In the watercolor configuration composed of wavy double contours, both assimilative and non-assimilative color spreading have been demonstrated depending on the luminance conditions of the inner and outer contours (IC and OC, respectively). This study investigated how the induced color in the watercolor configuration was modulated by combinations of the IC and the OC color, particularly addressing non-assimilative color spreading. In two experiments, the IC color was fixed to a certain color and combined with various colors selected from a hue circle centered at the background white color. Color spreading was quantified with a chromatic cancelation technique. Results showed that both the magnitude and the apparent hue of the color spreading were largely changed with the luminance condition. When the IC contrast (Weber contrast of the IC to the background luminance) was smaller in size than the OC contrast (higher IC luminance condition), the color spreading was assimilative. When the luminance condition was reversed and the IC contrast was greater than the OC contrast (lower IC luminance condition), the color spreading was non-assimilative and yellowish. When the color spreading was analyzed in terms of cone-opponent excitations, the results were consistent with the interpretation that the color spreading is explainable by a combination of chromatic diffusion from the IC and chromatically opponent induction from the OC. The color spreading in the higher IC luminance condition mainly reflected the chromatic diffusion by both (L-M) and S cone-opponent mechanisms. The non-assimilative color spreading in the lower IC luminance condition mostly reflected S-cone mediated opponent induction and the contribution of -S inducing mechanisms was differentially large. These findings provided several constraints on possible visual mechanisms underlying the watercolor effect.

No MeSH data available.