1. A color interpolation method of performing a color interpolation about a specified pixel in a Bayer array, comprising: inputting pixel data of the Bayer array in a predetermined color space; setting a two-dimensional matrix as a predetermined area around said specified pixel and calculating a horizontal evaluation value that is a pixel-value change evaluation value in a horizontal direction, and a vertical evaluation value that is a pixel-value change evaluation value in a vertical direction, by using all the pixel data of all color components in said predetermined area, the predetermined area being a pixel area of at least 5×5 around said specified pixel; comparing said horizontal evaluation value and said vertical evaluation value; and performing pixel interpolation using pixel values in said vertical direction about said specified pixel when it is judged from the comparing that a pixel value change in said horizontal direction is larger or performing pixel interpolation using pixel values in said horizontal direction about said specified pixel when it is judged from the comparing that a pixel value change in said vertical direction is larger.