Visual Cryptography for Secure Image Transmission: A Survey on Evolution, Optimization, and Future Research Trends

Abstract

Visual Cryptography (VC) is a new image security method allowing one to encrypt visual information into several random-looking shares, each of which keeps no secret about the original message. When these shares are properly superimposed, the concealed image is reconstructed visually without any computational decryption. First proposed by Naor and Shamir in 1994, VC has progressed to overcome a number of challenges including pixel expansion, loss of contrast, and color image processing. With recent developments, adaptive, semantic, and predictive methods have been added to improve the quality and precision of the reconstructed image while remaining computationally simple. Due to its resilience and visual decoding, VC is used in secure image sharing, watermarking, authentication, and medical data protection. This paper discusses the basic principles, current schemes, and recent advances in Visual Cryptography, highlighting its potential as an efficient, secure, and visually intuitive data protection scheme for contemporary digital systems.