In a method of a computing device for calibrating light channels, one or more channel options of an illumination selecting unit of the computing device are selected to turn on the one or more light channels of a light source device. A camera unit captures a first image of the light source device. A zone and a serial number of each light channel are marked on the first image. Each channel option of the illumination selecting unit is eliminated. The camera unit captures a second image of the light source device when a light channel is turned off. The first image and the second image are compared, and a correlation between the light channel that is turned off and the eliminated channel option is determined. The serial numbers of the channel options are modified and remapped according to correlations between each light channel and each channel option.