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The effect of background and illumination on color identification of real, 3D objects.

Allred SR, Olkkonen M - Front Psychol (2013)

Bottom Line: As in 2D scenes, we found relatively high but imperfect stability of color judgments under an illuminant shift.In contrast to 2D scenes, we found that background had little effect on average color judgments.Taken together, these results suggest that in real 3D scenes with ample cues to object segregation, the addition of a background may improve stability of color identification.

View Article: PubMed Central - PubMed

Affiliation: COVI Research Lab, Department of Psychology, Rutgers - The State University of New Jersey Camden, NJ, USA.

ABSTRACT
For the surface reflectance of an object to be a useful cue to object identity, judgments of its color should remain stable across changes in the object's environment. In 2D scenes, there is general consensus that color judgments are much more stable across illumination changes than background changes. Here we investigate whether these findings generalize to real 3D objects. Observers made color matches to cubes as we independently varied both the illumination impinging on the cube and the 3D background of the cube. As in 2D scenes, we found relatively high but imperfect stability of color judgments under an illuminant shift. In contrast to 2D scenes, we found that background had little effect on average color judgments. In addition, variability of color judgments was increased by an illuminant shift and decreased by embedding the cube within a background. Taken together, these results suggest that in real 3D scenes with ample cues to object segregation, the addition of a background may improve stability of color identification.

No MeSH data available.


Relationship between palette density (x-axis) and color constancy (blue symbols, y-axis) and variability (red symbols, y-axis) in the illumination (unfilled circles) and joint (filled circles) conditions. To aid in visualization, color constancy indices (red symbols) and variability values (blue symbols) were normalized to their respective maxima. All statistical tests in text were performed on non-normalized values. Lines are best fit to data collapsed across experimental condition.
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Figure 9: Relationship between palette density (x-axis) and color constancy (blue symbols, y-axis) and variability (red symbols, y-axis) in the illumination (unfilled circles) and joint (filled circles) conditions. To aid in visualization, color constancy indices (red symbols) and variability values (blue symbols) were normalized to their respective maxima. All statistical tests in text were performed on non-normalized values. Lines are best fit to data collapsed across experimental condition.

Mentions: This relationship is examined in Figure 9, where we plot color constancy (blue squares) and variability (red circles) as a function of number of palette chips in the cube region. Cube region was calculated as a circle with its center defined by the average color match in the baseline condition and its radius defined as the average variability of color matches in the baseline condition. The number of palette chips will clearly increase with cube region, and this increase may also be non-uniform. We confirmed that a wide range of radius values yielded the same pattern of results. To aid in visualization, both constancy indices and variability values were normalized to their respective maxima, but statistical tests were completed on the non-normalized data.


The effect of background and illumination on color identification of real, 3D objects.

Allred SR, Olkkonen M - Front Psychol (2013)

Relationship between palette density (x-axis) and color constancy (blue symbols, y-axis) and variability (red symbols, y-axis) in the illumination (unfilled circles) and joint (filled circles) conditions. To aid in visualization, color constancy indices (red symbols) and variability values (blue symbols) were normalized to their respective maxima. All statistical tests in text were performed on non-normalized values. Lines are best fit to data collapsed across experimental condition.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3823087&req=5

Figure 9: Relationship between palette density (x-axis) and color constancy (blue symbols, y-axis) and variability (red symbols, y-axis) in the illumination (unfilled circles) and joint (filled circles) conditions. To aid in visualization, color constancy indices (red symbols) and variability values (blue symbols) were normalized to their respective maxima. All statistical tests in text were performed on non-normalized values. Lines are best fit to data collapsed across experimental condition.
Mentions: This relationship is examined in Figure 9, where we plot color constancy (blue squares) and variability (red circles) as a function of number of palette chips in the cube region. Cube region was calculated as a circle with its center defined by the average color match in the baseline condition and its radius defined as the average variability of color matches in the baseline condition. The number of palette chips will clearly increase with cube region, and this increase may also be non-uniform. We confirmed that a wide range of radius values yielded the same pattern of results. To aid in visualization, both constancy indices and variability values were normalized to their respective maxima, but statistical tests were completed on the non-normalized data.

Bottom Line: As in 2D scenes, we found relatively high but imperfect stability of color judgments under an illuminant shift.In contrast to 2D scenes, we found that background had little effect on average color judgments.Taken together, these results suggest that in real 3D scenes with ample cues to object segregation, the addition of a background may improve stability of color identification.

View Article: PubMed Central - PubMed

Affiliation: COVI Research Lab, Department of Psychology, Rutgers - The State University of New Jersey Camden, NJ, USA.

ABSTRACT
For the surface reflectance of an object to be a useful cue to object identity, judgments of its color should remain stable across changes in the object's environment. In 2D scenes, there is general consensus that color judgments are much more stable across illumination changes than background changes. Here we investigate whether these findings generalize to real 3D objects. Observers made color matches to cubes as we independently varied both the illumination impinging on the cube and the 3D background of the cube. As in 2D scenes, we found relatively high but imperfect stability of color judgments under an illuminant shift. In contrast to 2D scenes, we found that background had little effect on average color judgments. In addition, variability of color judgments was increased by an illuminant shift and decreased by embedding the cube within a background. Taken together, these results suggest that in real 3D scenes with ample cues to object segregation, the addition of a background may improve stability of color identification.

No MeSH data available.