Lightweight robust watermarking for digital images using multiple domains

Abstract

Due to rapid growth of the Internet, digital contents such as text, audio, video and images are easily exchanged and disseminated by worldwide users. As a result, unauthorized duplication arises and becomes a serious issue which needs to be combat with. Therefore, several techniques has been researched and developed in guarding these contents; there are cryptography, encryption, steganography and watermarking. Out of these solutions, digital watermarking has emerged as a reliable technique in safeguarding the digital contents; which works on imperceptibly altering an original digital content to embed a message about the content, which can be later used for authentication purpose. Recently, many extensive researches have been carried out in the field of digital image watermarking due to various types of attacks against the digital images. Geometrical and image processing operations are two main types of attacks which can easily distort digital images. In order to resist those attacks, robust and fragile watermarks are required. A robust watermark is significantly essential in digital image watermarking whereby the embedded watermark in an image can be easily recovered even after it has been manipulated with geometrical or other attacks. Fragile watermark has the ability to detect any unauthorized changes which has been made to the embedded watermark. In this dissertation, we introduce a new lightweight robust watermarking approach based on edge features for spatial domain and wavelet domain. Edge features are chosen as a key factor of our proposed watermarking technique, since the edge information is considered to be robust feature which can withstand the scaling attack in a watermarked image. Moreover, embedding strategy works by embedding watermark in robust edges of a cover image. Meanwhile, an inverse process of embedding step is required in the watermark detection stage. In addition, the original cover image is not needed in validating the detected watermark. Experiments results demonstrated higher visual quality can be gained in spatial domain, due to less distortion to the watermarked image. On the other hand, wavelet domain revealed faster execution time with thresholding technique compared to spatial domain, which is based on edge detection through convolution approach. By overall experiment observations, we noticed that the proposed scheme is a simple algorithm with low computational complexity and consists of moderate image distortions. These are the three main factors contribute towards the robustness feature of our proposed scheme. Therefore this scheme turns out to be a lightweight watermarking and it is suitable to be implemented in many applications.