An image inputoutput apparatus and method includes a light source in optical communication with a spatial radiation modulator for projecting an output image and an image sensor for capturing an input image along a shared inputoutput path. A first ink mark is printed at a first printhead velocity. Also, a parallel running of plural inverters is simply performed by disposing PWM comparators corresponding to the first and second semiconductor switches. The information is obtained by demodulating data specified by a direction in a pattern of a bright line appearing in the second image data and corresponding to the exposure lines that is substantially perpendicular to the exposure lines. In some embodiments, the optical signal includes at least two different infrared wavelengths that are varied differently with time.