Hyperchaotic image encryption using phase-truncated fractional Fourier transform and DNA-level operation

•We propose a new image encryption method based on hyperchaotic system.•DNA encryption and phase-truncated fractional Fourier transform.•The image encryption method is feasible in both digital and optical styles.•The image encryption method is highly sensitive to the plain image.•Experimental results demonstrate that the proposal has strong robustness to different attacks.