When you need to quantify the color of ... an off-the-shelf RGB sensor and wire it up to an Arduino. Or you can go back to basics and build this reflective RGB sensor from an LED and a photocell.

[Fjord Carver] brings together an RGB LED and CdS Photoresistor to make a color sensor ... This time around it’s an Arduino doing the measuring instead of a PIC. So why isn’t that sensor ...

If you’d like to get more specific, Michael Klements’ Arduino-based scanner ... the sensor and measure colors, along with a 16×2 panel. An optional RGB LED attempts to copy the shade of ...