PURPOSE: To shorten time required for development in a pattern of a character data by a method wherein the character pattern of high frequency in use is preferentially registered in a font cache by outputting a test pattern.

CONSTITUTION: A test data is stored in a storage 6, and a test pattern is outputted based on the test data stored in the storage 6. When the test pattern is outputted, a character pattern developed in a pattern is stored in a font cache 8a, and the inputted character data is developed in a pattern by using the character pattern stored in the font cache 8a. An image is thus outputted based on the character pattern developed in the pattern.