A color image sensor is disclosed. The color image sensor includes a pixel array including a color filter array (“CFA”) overlaying an array of photo-sensors for acquiring a color image. The CFA includes first color filter elements of a first color overlaying a first group of the photo-sensors and second color filter elements of a second color overlaying a second group of the photo-sensors. The first color filter elements contribute to a first color channel of the color image and the second color filter elements contribute to a second color channel of the color image. The color image sensor further includes a color combiner unit coupled to combine the first color channel with the second color channel to generate a third color channel of the color image based on the first and second color channels. An output port is coupled to the pixel array to output the color image having three color channels including the first, second, and third color channels.