From what I've seen in spec sheets for modern color sensors (as of late 2020), the optimum sensing range is generally on the scale of centimeters. I am curious about the physics that can explain this limitation. Does it have to do with ambient light saturating the photocells/diodes/transistors on the sensor?
For example, if I wanted to sense the color of an object passing no closer than 5 feet away from the receiver in a well-lit environment, what sort of problems would I run into on the sensor output? Would anything change if the object was in a poorly-lit environment?
For the sake of the argument, let's assume I cannot use a camera or image processor for my application.