An image processing is provided. There is stored character string image data created by arranging at least one character image data item formed in response to text input. Processing image data is selected from character image data created in response to the 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. The registered image data is created by subjecting any of the character image data, the nonstandard character registration image data, and the blank image data, to a sizing process, and registering the resulting image data. Synthesized image data is formed by synthesizing the processing image data with at least part of the character string image data by carrying out a synthesis operation. The synthesis operation includes any of logic operations.