There are many factors affecting the brightness of these three LED beads, so it is better to compensate for the difference through drive circuitry or software. RGB LEDs have different brightness because they have different wavelengths. Light with a shorter wavelength needs more energy, so its bandgap needs to be larger. Yet a larger bandgap leads to a larger voltage drop, causing a different brightness. And in the process of producing LEDs, each patch of LED may have a slight difference. So we will choose a more effective way to control these three lights.
More reading: PCB Technology Applied To LED PCB Assembly
