The Color Checker is a checkerboard array of 24 scientifically prepared colored squares in a wide range of colors. Many of these squares represent natural objects of special interest, such as human skin, foliage & blue sky. These squares are not only the same color as their counterparts, but also reflect light the same way in all parts of the visible spectrum. Because of this unique feature, the squares will match the colors of natural objects under any illumination & with any color reproduction process. To evaluate the effect of varying any given factor, you simply compare the chart's color image photograph, television picture or printed sample with the actual Color Checker. This comparison may be made visually or through measurements of optical density. The Color Checker is proportioned so that when its image fills the frame of a 35mm camera, the images of the individual color squares are large enough to be measured with a densitometer. Dimensions: 9 1/4 x 13 1/2"