High-brightness LEDs are being touted as the next big revolution in lighting. They are already being used in applications such as architectural, theater, and automotive lighting and they are revolutionizing other markets such as LCD television backlighting. However, there are several challenges when it comes to lighting design with high-brightness LEDs. The exact color as well as flux can vary from part to part creating color variation from one lighting fixture to the next. As temperature increases, the flux decreases and color drifts, causing inconsistent flux and color output under different operating conditions. Combining these variances with the fact that many fixtures use a mixture of color from three or more LEDs to create the desired color, designers soon realize how challenging it is to create uniform color output from fixture to fixture and across operating conditions.