A data communication apparatus based on digital image processing includes a display that displays a color block array including color blocks corresponding to transmission data. The data communication apparatus also includes a camera that captures an image of a color block array displayed on a display of a transmitting side, and a storage that stores a code table including information about colors mapped to data values. The data communication apparatus further includes a Digital Signal Processor (DSP) that creates a color block array by converting transmission data to color blocks according to the code table during data transmission, identifies the color block array in the image captured by the camera, detects colors of color blocks in the color block array, and extracts data values corresponding to the detected colors during data reception.