The first stage of vision Name Date

Paragraph 1 Retina = over 100M light-sensitive cells Cell: Cones: sensitive to each color (red, green, blue), only at the center. Rods: less specialized The human retina is composed of over 100 million light-sensitive cells and there are two kinds of them. One is called Cones: Only about 6 million cells concentrate near the center. They are specialized to respond to red, green and blue colors. All of the remaining cells are called Rods. They are not specialized to a particular color but can receive a lot of different colors.

Paragraph 2 Grey-level picture = array of numbers The responses of retinal cells can be thought of as a two-dimensional array of the intensity values. These values can be represented as numerals. These numerals can be converted back into shades of grey which is called grey-level image. The picture on the left is such an image. The array of numbers in a box on the right correspond to the small rectangle in the picture. The larger the numeral, the more intense the light. So, for example, the right side of the red line are all 100’s corresponding the dark part. The left side of the line are all 200’s corresponding the white part. Grey-level picture = array of numbers