关键词: 块截断编码, 有序抖动, 数字水印, 图像压缩

Abstract:

To overcome the shortcomings of bad image quality or poor robustness of the current methods, a robust watermarking method based on adaptive order dither block truncation coding is proposed. Firstly, the image is adaptively divided into smooth regions, texture regions and edge regions using a quadtree segmentation, according to the information entropy and the variance. After that, these blocks are coded separately. Secondly, we exploit the bit plane obtained from adaptive order dither block truncation coding, and embed the watermark by changing the parity sum of the pixels within a window in the bit plane. Lastly, the watermark is retrieved with the parity sum and the majority voting strategy, not referring to the original image. The experimental results indicate that compared with the similar algorithm, the proposed method can achieve good image quality with a low compression rate, a high watermark rate and watermark rate flexibility. Moreover, it is robust to common attacks, especially to Salt ＆ Pepper noising, brightness adjustment, contrast adjustment, rotating and cropping attacks.

Key words: block truncation coding, order dither, digital watermarking, image compression