Watermarking in conjugate ordered dither block truncation coding images

Abstract

In this work, a novel method based on Block Truncation Coding (BTC) and halftoning technique is proposed for embedding watermarks into compressed images. Block truncation coding is a simple and efficient image compression technique. However, it yields images of unacceptable quality and significant blocking effects are seen when the block size used increases. A modified technique known as Ordered Dither Block Truncation Coding (ODBTC) is proposed to solve the above problems while maintaining the same compression capability. In addition, ODBTC can also be used to embed a watermark into the compressed image. This technique incorporates void-and-cluster method with block truncation coding and ordered dithering to carry out watermarking. Experimental results have indicated that the resulting image quality is better and the algorithm less complex as than traditional block truncation coding. Many forms of attacks are also carried out and confirm the robustness of the proposed methods.