Abstract: An image processing device includes a memory that stores a program and a processor that executes the program stored in the memory to perform a process. The process includes obtaining input image data that is generated by combining, in a horizontal direction, an effective display area of first image data and an effective display area obtained by expanding an effective display area of second image data in the vertical direction, the vertical size of the second image data being smaller than the vertical size of the first image data; and generating second output image data corresponding to the second image data by reducing the vertical size of second intermediate image data among first intermediate image data and the second intermediate image data, which are obtained by dividing the input image data in the horizontal direction, based on the vertical size of the effective display area of the second image data.