Using Electromagnetic Waves in the Wash

A few days ago I posted about using light waves to determine if clothing matched.  Today lets use the same technology to keep our whites white.  I once washed a brand new (nice) work shirt (on accident) with a blue sock.  The sock got blue on the shirt and I was unable to remedy the situation.  It would have been nice if my washing machine was equipped with a sensor that would alarm if it "noticed" a item of clothing with a significantly different wavelength of light.  It would work kind of like sonar bouncing light waves into the wash as it cycled and if it ever came across a blue sock among a sea of white it would either alarm or shut off the cycle or both.