To map the orientation-tuning property based on optical signals, we propose using correlation coefficients that can determine the correlation between the measured optical intensities and a Gaussian function at each pixel. The correlation coefficients at each pixel were computed by setting the spread (or SD) of the Gaussian function at 20 and 40 degrees. Comparison between the coefficients showed that, in the region representing cardinal lines, there was a significantly larger area that had a higher correlation with the 40 degree Gaussian function, in contrast to the region representing oblique lines, which had a larger area that displayed a higher correlation for the 20 degree Gaussian function. These results demonstrate that the cardinal orientation-sensitive cortical area tuned over a broader spectrum than the oblique orientation-sensitive cortical area did.