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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 2 shown in the CIE u′v′ chromaticity diagram. Results obtained when the IC color was +S (A), achromatic (B), and −S (C). Different symbols show the mean chromaticity coordinates necessary to cancel the induced color. The combination of symbol type and color designates the OC color (see also Figure 2C and Table 1). Error bars show ±1 SEM across observers. The IC colors were chosen on the S/(L+M) axis (vertical dotted line). They are therefore not shown graphically in the figure. Other aspects are the same as those shown in Figure 4.
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Figure 8: Chromatic cancelation data of Experiment 2 shown in the CIE u′v′ chromaticity diagram. Results obtained when the IC color was +S (A), achromatic (B), and −S (C). Different symbols show the mean chromaticity coordinates necessary to cancel the induced color. The combination of symbol type and color designates the OC color (see also Figure 2C and Table 1). Error bars show ±1 SEM across observers. The IC colors were chosen on the S/(L+M) axis (vertical dotted line). They are therefore not shown graphically in the figure. Other aspects are the same as those shown in Figure 4.

Mentions: The average cancelation settings were shown in the CIE u′v′ chromaticity diagram (Figure 8). Regardless of the IC color, almost all cancelation settings were located below the background white point and close to the +S/(L+M) direction, which indicates yellow color spreading. The different IC colors appear to change the magnitude of the yellow spreading and the IC of −S color produced the strongest spreading. It is important to notice that even when the IC color was +S (i.e., purple), the induced color was yellow. This means that non-assimilative yellow spreading was stronger than the typical assimilative color spreading in the present luminance condition where the IC contrast was greater than the OC contrast. Moreover, the yellow spreading was generally stronger when the OC color was +S (purple circle in each panel in Figure 8). It is noteworthy that a strong color spreading was induced when both the IC and OC colors were +S and thus there was no chromatic contrast between the IC and the OC (Figure 8A). Consequently, chromatic contrast between the double contours is not the necessary condition for non-assimilative color spreading. Similarly, when both the IC and OC colors were −S (yellow square in Figure 8C), color spreading of moderate size was induced. Finally, the effect of hue reversal between the IC and the OC color on color spreading was confirmed: strong color spreading was induced when the IC color was −S and the OC color was +S (purple circle in Figure 8C), whereas spreading was extremely small when the IC color was +S and the OC color was −S (yellow square in Figure 8A).


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 2 shown in the CIE u′v′ chromaticity diagram. Results obtained when the IC color was +S (A), achromatic (B), and −S (C). Different symbols show the mean chromaticity coordinates necessary to cancel the induced color. The combination of symbol type and color designates the OC color (see also Figure 2C and Table 1). Error bars show ±1 SEM across observers. The IC colors were chosen on the S/(L+M) axis (vertical dotted line). They are therefore not shown graphically in the figure. Other aspects are the same as those shown in Figure 4.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 8: Chromatic cancelation data of Experiment 2 shown in the CIE u′v′ chromaticity diagram. Results obtained when the IC color was +S (A), achromatic (B), and −S (C). Different symbols show the mean chromaticity coordinates necessary to cancel the induced color. The combination of symbol type and color designates the OC color (see also Figure 2C and Table 1). Error bars show ±1 SEM across observers. The IC colors were chosen on the S/(L+M) axis (vertical dotted line). They are therefore not shown graphically in the figure. Other aspects are the same as those shown in Figure 4.
Mentions: The average cancelation settings were shown in the CIE u′v′ chromaticity diagram (Figure 8). Regardless of the IC color, almost all cancelation settings were located below the background white point and close to the +S/(L+M) direction, which indicates yellow color spreading. The different IC colors appear to change the magnitude of the yellow spreading and the IC of −S color produced the strongest spreading. It is important to notice that even when the IC color was +S (i.e., purple), the induced color was yellow. This means that non-assimilative yellow spreading was stronger than the typical assimilative color spreading in the present luminance condition where the IC contrast was greater than the OC contrast. Moreover, the yellow spreading was generally stronger when the OC color was +S (purple circle in each panel in Figure 8). It is noteworthy that a strong color spreading was induced when both the IC and OC colors were +S and thus there was no chromatic contrast between the IC and the OC (Figure 8A). Consequently, chromatic contrast between the double contours is not the necessary condition for non-assimilative color spreading. Similarly, when both the IC and OC colors were −S (yellow square in Figure 8C), color spreading of moderate size was induced. Finally, the effect of hue reversal between the IC and the OC color on color spreading was confirmed: strong color spreading was induced when the IC color was −S and the OC color was +S (purple circle in Figure 8C), whereas spreading was extremely small when the IC color was +S and the OC color was −S (yellow square in Figure 8A).

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.