Light-receiving unit is set corresponding to a plurality of pixels. The pixel values of a plurality of pixels included in the light-receiving unit are added up, and read as light-receiving value to acquire a low-resolution frame image. The image processing device includes an estimation calculation section that estimates the pixel values of the pixels included in the light-receiving unit based on a plurality of low-resolution frame images, and an image output section that outputs a high-resolution frame image based on the estimated pixel values. The light-receiving value is read while sequentially performing a pixel shift process so that light-receiving units overlap each other. The estimation calculation section estimates the pixel values of the pixels included in the light-receiving unit based on the light-receiving values obtained by performing the pixel shift process.