I'm going to drive a Kingbright SMT RGB LED from a PIC with the intent to be able to display an apparent full colour spectrum. Plan is to "white balance" the thing using the current limit resistors and then PWM each channel, with 8 bit resolution if required. I'm wondering how many actual colours you need to display to make the thing scan through a convincing spectrum from a subjective human viewpoint. Also is there any algorithm that lets me calculate advance how to mix these colours, or have I just got to experiment to get a particular mixed colour? I'm aware that there are big differences in emission characteristics between the 3 LED's on the chip. I also wonder how much the linearity there is with respect to PWM drive level and output, and whether this varies between colours. All of this could make the output colour pretty arbitrary I guess.
Steve