Illumination Watermarking Technique Using Orthogonal Transforms

We propose the "illumination watermarking" technology with which the images of objects with no copyright protection can contain invisible digital watermarking, using spatially modulated illumination. This technology can be applied to objects without electronically embedded watermarking such as pictures painted by artists. We conducted experiments where one-bit binary data were embedded in one block that consisted of 8 x 8 pixels using the phase of the highest frequency component generated by DCT (discrete cosine transform) and WHT (Walsh-Hadamard transform). The experimental results revealed that embedded data could be read out with almost 100% accuracy in both cases.