A DWT-based Digital Video Watermarking Scheme with Error Cor(4)

Abstract. In this paper, a digital video watermarking algorithm is proposed. We present a novel DWT-based blind digital video watermarking scheme with scrambled watermark and error correcting code. Our scheme embeds different parts of a single watermark in

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Fig. 3. (a) Original watermark (b-i) Preprocessed watermark m0-m7 (j) Encrypted watermark m’0

In the next step, each small image is decomposed into 8 bit-planes, and a large image mn can be obtained by placing the bit-planes side by side only consisting of 0’s and 1’s. These processed images are used as watermarks, and totally 2n independent watermarks are obtained. To make the scheme more robust, the processed watermarks m are transformed to the wavelet domain and encrypted [10]. Sample preprocessed watermarks are shown in Fig. 3, where (a) is the original watermark, (b)-(i) represent the scrambled watermarks in the spatial domain, and (j) shows the encrypted watermark of (b), i.e., m’0.

Audio Watermark. Error correcting code is extracted from the watermark image and embedded in the audio channel as an audio watermark. This watermark provides the error correcting and detection capability for the video watermark. In detection phase, it would be extracted and used for refining the video watermark. Different error correcting coding techniques can be applied such as Reed-Solomon Coding Techniques [11] and Turbo Coding [12].

Error correcting code plays an important role to a watermark, especially when the watermark is corrupted, i.e., when it is damaged significantly. Error correcting code overcomes the corruption of a watermark, and can make the watermark survive through serious attacks. Moreover, the scheme also takes advantages of watermarking the audio channel, because it provides an independent channel for embedding the error correcting code, which gives extra information for watermark extraction. Therefore, the scheme is more robust than other schemes which only used video channel alone.

The key to error correcting is redundancy. Indeed, the simplest error correcting code is simply repeated everything several times. However, in order to keep the audio watermark inaudible, we cannot embed too much information into an audio channel. In our scheme, we apply averaging to achieve the error code. Within a small region of an image, the pixels are similar. Therefore, an average value of a small region can be