1. A color interpolation method comprising: a first step of inputting pixel data of Bayer array in a predetermined color space; a second step of setting a predetermined area around a specified pixel and calculating a pixel-value change evaluation value in a horizontal direction (hereinafter, referred to as a horizontal evaluation value) and a pixel-value change evaluation value in a vertical direction (hereinafter, referred to as a vertical evaluation value) by using pixel data of all color components in said predetermined area; a third step of comparing said horizontal evaluation value and said vertical evaluation value; and a fourth step of performing pixel interpolation using pixel values in said vertical direction about said specified pixel when it is judged from a comparison of said third step 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 a comparison of said third step that a pixel value change in said vertical direction is larger.