Two color channels clipping. So say the Green and Blue channel clip to 255. Not the Red channel so the complimentary to Red is Cyan thus that color is displayed.
Everything you thought you wanted to know about Histograms
Another exhaustive 40 minute video examining:
What are histograms. In Photoshop, ACR, Lightroom.
Histograms: clipping color and tones, color spaces and color gamut.
Histogram and Photoshop’s Level’s command.
Histograms don’t tell us our images are good (examples).
Misconceptions about histograms. How they lie.
Histograms and Expose To The Right (ETTR).
Are histograms useful and if so, how?
Low rez (YouTube):
http://www.youtube.com/watch?v=EjPsP4HhHhEHigh rez:
http://digitaldog.net/files/Histogram_Video.mov
