Figure.

Projections of IS/OS and COST and their cross-correlation. Visible correspondence is apparent between projections of the IS/OS (left) and COST (center). Quantitatively, this correspondence manifests in the peak of the cross-correlation between IS/OS and COST, the central 21 × 21-pixel region of which is shown here (right). The peak value of 0.504 is equal to the Pearson correlation between the two images, and corresponds to a negligible P value. Fourier transformation of the projections had peaks at the expected spatial frequencies of the cones, derived from histological measurements.²⁶ The high correlation and similar power spectra suggest high correspondence between the structures responsible for the images, contrary to Spaide's claim.