Digital watermarking technique using brightness-modulated light

We propose a novel technology that can prevent the illegal use of images of objects that do not have watermarking. This technique uses illumination that invisibly contains the watermarking. As the illumination for the object contains watermarking, the image of the object taken by the camera also contains watermarking and this watermarking can be extracted by image processing. We conducted experiments where one-bit binary data were embedded in one block that consisted of 8 times 8 pixels using the phase of the highest frequency component generated by DCT. The experimental results revealed that embedded data could be read out extremely accurately, reaching 100% with the majority method, which used three data embedded in three separated blocks. The experimental results demonstrated the feasibility of the technology we propose.