There are several types of LED drivers out in the world and many use a method called Pulse Width Modulation (PWM) to control the brightness (or luminance) of an LED. When wanting to gradually illuminate an LED to full brightness, one convention is to make equal increments in the duty cycle until it reaches 100%. This is shown in Figure 1-a. The changes of the LED brightness, however, do not move in parallel to the linear changes in the duty cycle. Instead, the LED appears to go from completely off to near full brightness very quickly. Subsequent changes in brightness then become nearly imperceptible to an observer. This is shown in Figure 1-b.