I'm not sure what you mean by a white comb with no photo.
Chickens can get a whitish coating on their combs that could mean dryness. But if you mean that a very red comb has totally lost all it's color, this would be a sign of total loss of blood flow in the comb - but usually they might turn a purple color or maybe pink. In severe cases of frost bite of the comb, the comb turns black.
I've never seen a red comb turn white. I'll post this on our Facebook page: https://www.facebook.com/RaisingChickensORG/ and see if anyone can answer this.