1. An image processing device comprising: a processor; and a memory storing computer-readable instructions therein, the computer-readable instructions, when executed by the processor, causing the image processing device to perform: acquiring first image data representing a first image and second image data representing a second image, the first image showing a part of a target object and the second image showing another part of the target object, the first image including a first edge; generating a plurality of first pixels so as to be arranged outside the first image and along the first edge by using a plurality of pixels that are arranged inside the first image and along the first edge, the plurality of first pixels not being included in the first image; determining a relative position between the first image and the second image by using the plurality of first pixels; and generating arranged image data representing an arranged image in which the first image and the second image are arranged according to the relative position so that the arranged image shows the target object.