<p>The increasing reliance on visual data transmission across distributed and cloud-based environments requires image encryption frameworks that provide both strong cryptographic guarantees and practical computational efficiency. Conventional image encryption schemes frequently rely on heuristic transformations whose security is primarily evaluated through statistical analyses, often lacking formal resistance against emerging post-quantum threats. A layered post-quantum image encryption framework is presented, integrating lattice-based key establishment, deterministic image scrambling, and authenticated encryption within a unified architecture. A shared secret is established using the sntrup761 key encapsulation mechanism, providing IND-CCA security under lattice-based assumptions. The derived session key is expanded using HKDF into independent keys for permutation scheduling and encryption, enabling separation between cryptographic security and image transformation layers. A nondeterministic finite-state scheduling mechanism drives spin-matrix-based scrambling to enhance spatial diffusion, while authenticated encryption with associated data ensures confidentiality and integrity through strict verification prior to image recovery. Security analysis shows that post-quantum security comes from the lattice-based key encapsulation mechanism rather than the image-transformation layer, and demonstrates robustness against adaptive adversarial models, while computational evaluation indicates linear scalability with image size. Statistical and robustness analyses further confirm strong diffusion properties and stable scrambling-layer behavior under noise and occlusion conditions. The proposed framework bridges standardized post-quantum cryptography with lightweight image-oriented transformations, providing a structured and practical approach for secure visual data transmission.</p>