Based on spread spectrum communications

the approach concerns mainly a series of techniques: the substitution of DCT of 2D in frequency domain of the owner image

the use of selection-and-group tactics conducted by means of JND threshold of gray-image and the multiple-based work underlying DCT frequency domain of the owner image

the classification of embedded watermarking with AC of intermediate frequency

the performance at random on AC of high-low frequency that embedded

and the realization of digital blind watermarking of multiple gray watermarking in order to transmit it by the mode of carrier wave.This algorithm evaluates the capacity of the digital watermarking and extracts the digital watermarking without the original watermark and the owner image.The experimental results proves that the algorithm is of good robustness and renitency for the procedures

like filtering

adding noise

clipping

JPEG compression.