<p>Existing chaotic image encryption schemes have made progress in improving keystream randomness and dynamic substitution; however, the coupling between the underlying chaotic dynamics, S-box construction, and the overall encryption architecture remains limited, especially for high-resolution color images. To address this issue, this paper proposes a color image encryption method that integrates a CML–ECA neurodynamic chaotic system with a TV-BST-based permutation–diffusion framework. Specifically, an ECA–CML composite chaotic model is first established, in which a local-entropy adaptive coupling strategy is combined with Wilson–Cowan excitatory–inhibitory neurodynamic feedback to modulate the Logistic–sine control parameters and lattice states, thereby generating spatiotemporal chaotic sequences with enhanced sensitivity, entropy, and finite-precision robustness. The resulting chaotic flow is then used to construct an initial S-box through a Fisher–Yates shuffle, which is further optimized by a genetic mechanism under joint cryptographic objectives to obtain a high-quality chaotic S-box. At the architecture level, the TV-BST module performs key-dependent row–column permutation for global scrambling, while each color channel undergoes forward and backward chained diffusion together with S-box substitution. Experimental results show that the proposed method produces nearly uniform histograms, low adjacent-pixel correlation, high key sensitivity, and NPCR/UACI values close to their theoretical expectations. In addition, the scheme exhibits robustness against common disturbances such as noise contamination and cropping attacks. These results indicate that the proposed co-designed framework provides an effective and secure solution for color image encryption.</p>