The rapid adoption of cloud computing for multimedia storage and transmission has intensified concerns related to data confidentiality, integrity, and unauthorized interception, particularly for sensitive image data. Conventional single-layer cryptographic techniques are increasingly inadequate against advanced cyber threats, dynamic attacks, and emerging quantum adversaries. This paper presents a comparative analysis of a hybrid cryptographic framework designed to enhance secure image transmission in cloud environments by integrating encryption, encoding, and covert communication mechanisms. The proposed framework combines AES, One-Time Pad (OTP), and RSA to achieve secure and adaptive key management with time-limited access control, ensuring strong confidentiality and resistance to key compromise. To preserve image integrity and minimize transmission distortion, a Federated Wavelet-Based Convolutional Quotient Multipixel Value Differencing (F-WCQMVD) scheme is employed, enabling efficient and privacy-preserving encoding across distributed cloud nodes. Furthermore, isogeny-based cryptography integrated with spread spectrum steganography is utilized to provide post-quantum security and stealthy communication, concealing the very existence of sensitive image data during transmission. A comprehensive comparative evaluation is conducted against conventional cryptographic, steganographic, and hybrid approaches using metrics such as Peak Signal-to-Noise Ratio (PSNR), Mean Squared Error (MSE), Structural Similarity Index (SSI), encryption and decryption time, latency, and security efficiency. Experimental results demonstrate that the proposed hybrid framework significantly outperforms existing methods in terms of image quality preservation, computational efficiency, robustness to steganalysis, and quantum resistance. The findings confirm that the integration of adaptive encryption, wavelet-based federated encoding, and isogeny-driven covert communication provides a scalable and resilient solution for secure image transmission in modern cloud environments.