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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.


(A) Variability of color matches in the illumination (brown squares), background (magenta circles) and joint (green triangles) conditions (y-axis) as a function of variability in the baseline condition (x-axis). Colored lines are best-fit to data in the least-squares sense. Black diagonal line indicates identity. (B) Variability in the labeled experimental condition averaged across cubes. Error bars are s.e.m. across cubes (n = 16). In both (A) and (B) variability was defined as the average distance in color space space between each observer's match and the average chromaticity of matches in that condition.
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Figure 7: (A) Variability of color matches in the illumination (brown squares), background (magenta circles) and joint (green triangles) conditions (y-axis) as a function of variability in the baseline condition (x-axis). Colored lines are best-fit to data in the least-squares sense. Black diagonal line indicates identity. (B) Variability in the labeled experimental condition averaged across cubes. Error bars are s.e.m. across cubes (n = 16). In both (A) and (B) variability was defined as the average distance in color space space between each observer's match and the average chromaticity of matches in that condition.

Mentions: We compared variability in the baseline condition to variability in each experimental condition (Figure 7). If the basic processes underlying color matching are not altered by either the illumination shift or the addition of a background, then the data should fall along the identity line. However, we found that variability in the illumination condition was significantly different than in the baseline condition (brown squares above the line in Figure 7A, two-tailed paired t-test, p < 0.005). In contrast, adding a background significantly decreased the between-observers variability in color matches (magenta circles below the line in Figure 7A; two-tailed, paired t-test, p < 0.05).


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

Allred SR, Olkkonen M - Front Psychol (2013)

(A) Variability of color matches in the illumination (brown squares), background (magenta circles) and joint (green triangles) conditions (y-axis) as a function of variability in the baseline condition (x-axis). Colored lines are best-fit to data in the least-squares sense. Black diagonal line indicates identity. (B) Variability in the labeled experimental condition averaged across cubes. Error bars are s.e.m. across cubes (n = 16). In both (A) and (B) variability was defined as the average distance in color space space between each observer's match and the average chromaticity of matches in that condition.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: (A) Variability of color matches in the illumination (brown squares), background (magenta circles) and joint (green triangles) conditions (y-axis) as a function of variability in the baseline condition (x-axis). Colored lines are best-fit to data in the least-squares sense. Black diagonal line indicates identity. (B) Variability in the labeled experimental condition averaged across cubes. Error bars are s.e.m. across cubes (n = 16). In both (A) and (B) variability was defined as the average distance in color space space between each observer's match and the average chromaticity of matches in that condition.
Mentions: We compared variability in the baseline condition to variability in each experimental condition (Figure 7). If the basic processes underlying color matching are not altered by either the illumination shift or the addition of a background, then the data should fall along the identity line. However, we found that variability in the illumination condition was significantly different than in the baseline condition (brown squares above the line in Figure 7A, two-tailed paired t-test, p < 0.005). In contrast, adding a background significantly decreased the between-observers variability in color matches (magenta circles below the line in Figure 7A; two-tailed, paired t-test, p < 0.05).

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.