What is the difference between color and brightness contrast?
One important distinction between sets of colors is whether they create brightness (achromatic) or color (chromatic) contrast. Both kinds of contrast make objects stand out from their backgrounds. However, there are significant differences in the properties of color and brightness contrast. A designer who understands these fundamental differences will find him/herself able to use color much more effectively. The visual system has separate achromatic and chromatic subsystems for seeing brightness and chromatic contrast. The achromatic part has about 5 times better visual acuity than the chromatic system. (NTSC TV coding doesn’t even bother transmitting the color of fine detail because the viewer wouldn’t be able to resolve it anyway.) The higher the brightness contrast, the better the spatial resolution. If the viewer must resolve fine detail, as when reading small text, then there must be a high degree of brightness contrast and color contrast will matter little. A border that has chro
