
Accurately detecting colours without needing calibration has always been an issue with robots for both Robocup Junior Rescue Line and Rescue Maze competitions.
If the sensor can detect colours itself, it might have issues depending on the range of shades for each colour. For example: Lego EV3 colour sensors are known for being bad at detecting shades of green other than Lego Dark Green.
Using the RGB (Red, Green and Blue) values from a colour sensor does allow the developer to interpret the values and decide which colour that represents. However, using HSI (Hue, Saturation and Intensity) makes this exercise simple and accurate.