Comparison of Image Encryption Methods Using Hybrid Frequency Domain Transforms and Chaotic Maps

This paper presents a comparative study of hybrid image encryption algorithms combining frequency-domain transforms with chaotic scrambling.Three methods are analyzed: DCT + Arnold, WHT + Arnold, and DCT WHT + Arnold.The Fast Walsh-Hadamard Transform (FWHT) is used to enhance computational efficiency.Cryptographic strength and reconstruction quality are evaluated using entropy, correlation coefficients, NPCR, UACI, MSE, and PSNR.Results show that WHT + Arnold (FWHT-based) offers the fastest processing with high security and lossless decryption, while the hybrid DCT WHT + Arnold also demonstrates strong cryptographic characteristics.