# Reflected light measure This example uses a color sensor to measure the reflected light on the dark and light surface and set the light/dark thresholds. ```blocks sensors.color3.onLightDetected(LightIntensityMode.Reflected, Light.Dark, function () { brick.showString("dark", 2) }) sensors.color3.onLightDetected(LightIntensityMode.Reflected, Light.Bright, function () { brick.showString("bright", 2) }) console.sendToScreen() console.log("move color sensor") console.log("over DARK color") console.log("press ENTER when ready") brick.buttonEnter.pauseUntil(ButtonEvent.Pressed) sensors.color3.setThreshold(Light.Dark, sensors.color3.light(LightIntensityMode.Reflected) + 5) console.logValue("dark", sensors.color3.threshold(Light.Dark)) console.log("move color sensor") console.log("over BRIGHT color") console.log("press ENTER when ready") brick.buttonEnter.pauseUntil(ButtonEvent.Pressed) sensors.color3.setThreshold(Light.Bright, sensors.color3.light(LightIntensityMode.Reflected) - 5) console.logValue("bright", sensors.color3.threshold(Light.Bright)) forever(function () { brick.showValue("reflected light", sensors.color3.light(LightIntensityMode.Reflected), 1) }) ```