Method for determining color of an illuminant in an image based on histogram data

A method for determining a color of a scene illuminant from a digital version of a natural image comprising steps of:

• measuring colors of pixels in the image;
• representing the pixel colors in electronic form with the aid of a computer;
• dividing, with the aid of the computer, the pixels into subsets corresponding to a limited range of luminance;
• and
• detecting, with the aid of the computer, a measure of scene illuminant as a chrominance of specularly reflected light as recorded in the limited luminance range.

An electronic method for compensating for color-cast in a recorded image comprising steps of:

• representing colors of pixels in the image in electronic form with the aid of a computer;
• generating a chrominance histogram with the aid of the computer;
• isolating with the aid of the computer non-circular neighborhoods around peaks in the chrominance histogram;
• detecting with the aid of the computer lines along which lie major axis of isolated neighborhoods;
• selecting with the aid of the computer a convergence-chrominance value near which the detected lines converge;
• and
• electronically with the aid of the computer changing pixel values with a transform that maps the convergence-chrominance to another color, thereby producing a compensated electronic image.