Adaptive color plan interpolation in single sensor color electronic camera

In apparatus for processing a digitized image signal obtained from an image sensor having red, green, and blue color photosites aligned in rows and columns that generate at least three separate color values but only one color value for each photosite location, said apparatus including means for interpolating the color values for each photosite location so that each photosite has the three separate color values, said means for interpolating comprising:

• means for storing the digitized image signal;
• a processor operative with said storing means for generating an appropriate color value missing from a photosite location by the interpolation of an additional color value for such photosite locations from color values of different colors than the missing color value at nearby photosite locations, said processor including
• means for obtaining Laplacian second-order values and gradient values in at least two image directions from nearby photosites of the same column and row;
• means for adding the Laplacian second-order values and the gradient values to define a classifier and for selecting a preferred orientation for the interpolation of the missing color value based upon the classifier;
• and
• means for interpolating the missing color value from nearby multiple color values selected to agree with the preferred orientation wherein neighboring color values of the same color are averaged and corrected by neighboring color values of a different color value.