This paper investigates a colour image encryption and decryption method based on a fractional-ordered hyperchaotic system coupled with an improved DNA model and Euler circuit pattern-based scrambling process. To achieve a comparatively lower computational burden with higher effectiveness, an improved fractional-order 3D hyperchaotic system utilizing the generalized form of state variable with parametric power ( \({x}_{2}^{d}\) ) is proposed. The rich dynamical behaviours of this system are analyzed in several aspects, such as hyperchaos, inversion symmetric co-existence, attractor merging, offset boosting, and complexity analyses, which produce an efficient set of pseudo-random sequences for the new encryption method. A novel pixel scrambling process is developed based on the user input Euler circuit pattern(s). For the binary encoding process, an improved generalized sDNA model is developed with \({2}^{t}\) ( \(t=\text{1,2},3,\ldots \) ) letters, instead of the four letters, with a simple mutational rule in comparison to existing DNA encoding methods. Such Euler pattern-based scrambling and the improved DNA model are not adequately addressed by previous encryption techniques. Additionally, a new box scrambling technique is employed to boost the randomness in the encrypted image. A comprehensive investigation is carried out considering several factors like key security, decryption quality, and resilience to statistical and differential attacks which conclude the effectiveness to resilient several assaults. Furthermore, the study of clipping and noise attacks shows how effective and resilient the suggested approach is against external noise attacks and data loss during the transmission of encrypted images.
