Max-Plus Algebra-Based Morphological Wavelet Transform Watermarking for Highly-Parallel Processing with Mobile Embedded Processor

This paper presents Max-plus algebra-based Morphological wavelet Transform (MMT) watermarking, which is a novel mobile-dedicated information data embedding method. The performance of watermarking processing is considered a very important factor in embedded processors, which are applied to mobile devices. This is because, in the case of embedding information data in digital contents for mobile application, real-time processing speed is more important than data security and image quality. The proposed MMT watermarking method can be defined by nonlinear operation (maximum or minimum search) and standard sum. Thus, while the proposed watermarking method only uses integer representation for all variables with embedding operation, the conventional watermarking method has to calculate complex numbers, trigonometric functions, and floating-points for restricting watermarked-image distortion. As a result, the proposed method can reduce the number of clock cycles to drastically less than those of conventional transform-based watermarking. The processing time of the MMT watermarking is about 1/28, 1/2720, and 1/4364 shorter than those of Haar Wavelet Transform (HWT), Discrete Cosine Transform (DCT), and Fast Fourier Transform (FFT), respectively. Furthermore, the practical-use processing time of the MMT watermarking with the evaluation board for the massive-parallel Single Instruction Multiple Data (SIMD) matrix processor is found to be about 96% shorter than that of the HWT watermarking method on the BeagleBoard-xM, which is used the ARM Cortex-A8. To compare the watermarked and extract image distortion, the PSNR values of MMT, DCT and HWT watermarking are calculated. The PSNR value of the proposed MMT watermarking is suitable for practical use with 5-bit watermark embedded information, which can keep maintain image quality for both watermarked and extract images. Consequently, the proposed MMT watermarking algorithm can achieve an efficient real-time watermarking scheme for mobile device applications.