Recent neuroimaging research suggests that early visual processing circuits are activated similarly during visualization and perception but have not demonstrated that the cortical activity is similar in character. We found functional equivalency in cortical activity by recording evoked potentials while color and luminance patterns were viewed and while they were visualized with the eyes closed. Cortical responses were found to be different when imagining a color pattern vs. imagining a checkerboard luminance pattern, but the same when imagining a color pattern (or checkerboard pattern) vs. seeing the same pattern. This suggests that early visual processing stages may play a dynamic role in internal image generation, and further implies that visual imagery may modulate perception. (Contains 4 figures and 1 table.)