IMAGE PROCESSING SYSTEM HAVING IMAGE FORMING APPARATUS AND PRINTER APPARATUS

An image processing system includes a printer driver converting input image data into a printing data, and a printer apparatus performing data output using the converted image data. The printer driver or the printer apparatus includes at least an image forming apparatus. The image forming apparatus includes a data buffer storing an input printing data, a judgment portion for making judgment whether a define statement of a predetermined character is included in data stored in the data buffer; and a line screen value converting portion for converting a line screen definition for performing halftone printing of the predetermined character when a define statement of the predetermined character is contained in data stored in the data buffer.