YesEdge detection plays an important role in human vision,
and although it is clear that there are luminance edge
detectors, it is not known whether there are chromatic
edge detectors as well.We showed observers a horizontal
edge blurred by a Gaussian filter (with widths of r ¼
0.1125, 0.225, or 0.458) embedded in blurred Brown
noise. Observers had to choose which of two stimuli
contained the edge. Brown noise was used in preference
to white noise to reveal localized edge detectors. Edges
and noise were defined by either luminance or chromatic
contrast (isoluminant L/M and S-cone opponent).
Classification image analysis was applied to observer
responses. In this analysis, the random components of the
stimulus are correlated with observer responses to reveal
a template that shows how observers weighted different
parts of the stimulus to arrive at their decision.We found
classification images for both luminance and isoluminant
chromatic stimuli that had shapes very similar to
derivatives of Gaussian filters. The widths of these
classification images tracked the widths of the edges, but
the chromatic edge classification images were wider than
the luminance ones. These results are consistent with
edge detection filters sensitive to luminance contrast and
isoluminant chromatic contrast.Royal Society Travel Grant IE130877 and in part by Canadian Institutes of Health Research (CIHR) grant MOP-1081
