A new semi-blind watermarking algorithm using ordered Hadamard transform

Abstract

An efficient and fast watermarking algorithm based on ordered Hadamard transform (HT) is proposed. Since it uses a few information of watermark image in secret key, it is categorised as a semi-blind method. In our algorithm, both host and watermark images are decomposed into non-overlapping blocks. Next, they are mapped into transform domain as Hadamard coefficients. Then, several high frequency AC components of host image are substituted with watermark coefficients without using any strength factor. Not employing this factor guarantees the embedded image to be retrieved with primary quality. Moreover, using HT offers several advantages of fastness, higher image fidelity, greater reliability of watermark detection and higher data hiding capacity. The experimental results show that our method keeps the quality of host image and is robust to common attacks. Compared to frequency domain and hybrid methods, it has advantages of shorter processing time, acceptable robustness and ease of hardware implementation.

Keywords:

• Image security
• Image watermarking
• Frequency domain
• Ordered Hadamard transform
• Image processing attacks