Bouakkaz, Fatima2025-10-302025-10-302024http//localhost:8080/jspui/handle/123456789/13424This work provides a comprehensive overview of quality assessment and security techniques in multimedia systems. It begins by analyzing the factors that affect image quality, such as degradation, noise, and compression artifacts, and discusses both subjective and objective methods for quality evaluation. It then explores multimedia security mechanisms, including digital watermarking, cryptography, and steganography, emphasizing their roles in protecting content integrity, authenticity, and ownership. Additionally, the study addresses propagation channel characterization and advanced transmission strategies, such as MIMO systems and joint source-channel coding, which enhance multimedia delivery in complex network environments. The overall objective is to present an integrated understanding of how to preserve and secure multimedia data from acquisition to transmission.enImage quality, multimedia security, watermarking, cryptography, steganography, MIMO systems, propagation channel, image degradation, signal processing, digital rights management.Other