An image editing apparatus which is capable of assembling a plurality of original documents on one sheet as an output data without impairing the legibility of characters in the reduced images. This apparatus reads images in original documents, detects the size of characters in the read original documents, sets the number of original document images to be produced per page for the output data based on the detected character size, and reduces and edits the read image data into the output data having the set number of original document images per page.