Our visual field, the entire view of what we can see when we look out into the world, is divided into billions of tiny spots or pixels. Each pixel is filled with atoms and molecules that are in vibration. The retinal cells in the back of our eyes detect the movement of those atomic particles. Atoms vibrating at different frequencies emit different wavelengths of energy, and this information is eventually coded as different colors by the visual cortex in the occipital region of our brain. A visual image is built by our brain's ability to package groups of pixels together in the form of edges. Different edges with different orientations - vertical, horizontal and oblique, combine to form complex images. Different groups of cells in our brain add depth, color and motion to what we see.
Jill Bolte Taylor, My Stroke of Insight: A Brain Scientist's Personal Journey
edge-detection, perception, sight