This paper proposes a digital image encryption algorithm based on dynamic DNA encoding and operations using hyper digital chaos in frequency-domain. The chaotic DNA encoding and operations are applied to diffuse and scramble both of the amplitude and phase components in frequency-domain. The proposed multi-fold encryption algorithm is evaluated via numerical verification, in which the ideal performances of the encrypted images are achieved, in terms of uniformity in histogram, entropy as well as correlation. The results show that, since the chaotic diffusion and scrambling are introduced in the proposed encryption, each cipher-pixel is influenced by all of the plain and cipher-pixels, which improves the plain-text sensitivity of the encrypted image, and the secure performances against the differential attacks. Moreover, high security level of the encrypted image is achieved with a huge key space, due to the extremely high sensitivity of hyper digital chaos applied in the proposed encryption scheme, therefore it has the strong capability to resist brute-force attacks. In addition, the statistical characteristic of the original image is destroyed completely, thus it improves the security against the statistical attacks.