An image processing device creates reduced image data based on original image data indicative of an original image. The original image is divided into original grids each corresponding to a set of original pixel data. The reduced image is divided into reduced grids each corresponding to a set of reduced pixel data. The image processing device acquires, for each set of reduced pixel data, original pixel data corresponding to the original grid whose part is superposed on the reduced grid corresponding to the each set of reduced pixel data when the reduced image is partially superposed on the original image such that the reduced image is shifted. The reduced pixel data is produced by calculating a weighted average of the original pixel data based on size ratio of the part of original grid superposed on the reduced grid to a size of the reduced grid.