1. An imaging device comprising: an image sensor that includes an array of pixels that respectively correspond to a plurality of colors; an imaging control section that performs a control process that acquires a captured image while sequentially shifting a position of an object image on the image sensor by a shift amount that is smaller than a pixel pitch of the image sensor; an image conversion section that calculates luminance values and color difference values based on pixel values of the acquired captured image that respectively correspond to the plurality of colors, and outputs a luminance image formed by the calculated luminance values and a color difference image formed by the calculated color difference values; an estimation calculation section that calculates an estimated luminance value of each pixel of a high-resolution image having a resolution higher than a resolution obtained by the pixel pitch of the image sensor based on the luminance image, and calculates an estimated color difference value of each pixel of the high-resolution image based on the color difference image; and a pixel value conversion section that converts the estimated luminance value and the estimated color difference value into RGB pixel values of each pixel of the high-resolution image.