Image sensor apparatus and method for scene illuminant estimation

A method for estimating a scene illuminant in an image sensor device, comprising:

• generating a plurality of illuminant characteristic curves;
• capturing pixel data corresponding to a scene under a scene illuminant;
• generating a pixel characteristic curve for a subset of the pixel data in a color space subset;
• comparing the pixel characteristic curve to the plurality of illuminant characteristic curves to estimate the scene illuminant;
• generating a plurality of image sensor device responses to a training set under a plurality of candidate illuminants, the training set comprising a plurality of natural surfaces;
• normalizing the plurality of image sensor device responses and projecting the plurality of normalized image sensor device responses into the color space subset;
• and
• finding a chromaticity trend in the plurality of normalized image sensor device responses in the color space subset to generate the plurality of illuminant characteristic curves,
• wherein generating the plurality of illuminant characteristic curves comprises measuring spectral sensitivities of the image sensor device for red, blue, and green color channels, and
• wherein finding the chromaticity trend in the plurality of normalized image sensor device responses comprises applying a statistical trend analysis to the plurality of normalized image sensor device responses to determine a plurality of trend coefficients, the plurality of trend coefficients representing the plurality of illuminant characteristic curves.