An image processing device, an image processing system, and a method of processing an image. The image processing device and the method includes displaying a first screen and a second screen using an image processing device connected to an image display apparatus, controlling a display to display one of the first screen and the second screen on the image display apparatus, acquiring from the image display apparatus discrimination data including at least data for distinguishing between the first screen and the second screen, and determining a partition between the first screen and the second screen based on the discrimination data. The image processing system includes an image display apparatus and at least one information processing device.