Abstract: The discriminability of character data that is displayed on a screen is improved by performing a color conversion on the character data. More specifically, a color conversion system is provided which comprises: extraction means for extracting character data including color data; conversion means for converting the extracted color data based on a predetermined color conversion rule; and output means for outputting the character data and the obtained color data to the application. The color conversion rule for this invention is set in advance so as to attain a specific objective (e.g., to enable a color-blind user to easily identify displayed characters). A single color conversion process and/or a process that provides the sequential conversion of multiple character colors at a constant time interval may be used.