Images have become a strategic digital asset that powers creative industries, e–commerce, and data–driven services. However, modern editing tools and large–scale sharing platforms have made copyright infringement, unauthorized redistribution, and covert manipulation easier to perpetrate and harder to detect. These risks lead to financial losses and weaken trust in digital ecosystems, creating an urgent need for technical protections that complement legal remedies. This paper presents a comprehensive survey of technologies and approaches for image copyright protection, with a particular emphasis on digital watermarking, deep learning-based methods, and blockchain-enabled frameworks. We systematically examine the principles, mechanisms, and applications of these techniques, evaluating their strengths, limitations, and potential synergies. In addition, we explore how these technologies can be effectively integrated into practical systems for secure, reliable, and scalable copyright protection of images. Finally, we identify existing challenges and propose promising future research directions to advance the state of the art in image copyright protection.