1. A pixel interpolation device comprising: a same-color pixel mixture device for, in a color image in which a basic array pattern including a pixel of a first color and pixels of second and third colors having a lower contribution to brightness than the pixel of the first color is repeatedly arranged in a row direction and a column direction, mixing the pixels of the first color such that at least a first type of pixels of the first color which are arranged in the same row as the pixel of the second color or the pixel of the third color and a second type of pixels of the first color which are different from the first type of pixels of the first color and are arranged in the same column as the pixel of the second color or the pixel of the third color are separately mixed with each other in a pixel mixture block and for separately mixing the pixels of the second color and the pixels of the third color in the pixel mixture block such that a process of mixing the pixels of the same color is performed for each pixel mixture pattern having a plurality of pixels in the row direction and the column direction, thereby obtaining a plurality of types of mixed pixels of the first color, a mixed pixel of the second color, and a mixed pixel of the third color for each pixel mixture pattern; a correlation determination device for determining whether a correlation direction is the column direction or the row direction in the color image, on the basis of the plurality of types of mixed pixels of the first color obtained by the same-color pixel mixture device; and an interpolation device for generating an interpolation pixel of the first color, an interpolation pixel of the second color, and an interpolation pixel of the third color for each pixel mixture pattern, using the plurality of types of mixed pixels of the first color, the mixed pixel of the second color, and the mixed pixel of the third color obtained by the same-color pixel mixture device, on the basis of the determination result of the correlation determination device.