1. An image processing device comprising: character string image data-storing means for storing character string image data created by arranging at least one character image data item formed in response to text input; processing image data-selecting means for selecting processing image data from character image data created in response to said text input, nonstandard character registration image data created by nonstandard character registration, blank image data formed of data representing a blank image area, and registered image data created by subjecting any of said character image data, said nonstandard character registration image data, and said blank image data, to a sizing process, and registering the resulting image data; and synthesized image data-forming means for forming synthesized image data by synthesizing said processing image data with at least part of said character string image data by carrying out a synthesis operation, said synthesis operation including any of logic operations.