An image processing apparatus of the present invention includes a control panel for allowing an application mode selector an image quality mode to be selected. A reading unit generates a preselected color image signal by reading a document image. A scanner corrector executes image processing with the color image signal in accordance with the application and the image mode selected by on the control panel to thereby generate color image data. A storage stores the image data generated by the scanner corrector and information representative a processing mode based on the application and image mode selected on the control panel. A data compressor/expander selectively compresses or expands the image data. A data format converts the format of the image data stored in the storage in matching relation to the processing mode.