Abstract: Aiming at the problems of poor security and slow encryption efficiency of color image, a spatial color image composite encryption algorithm based on chaotic mapping is designed. The depth residual network is constructed, the jump connection is added in the residual unit block, the nonlinear mapping of noisy image is created, and the activation function is moved to the convolution layer to accelerate the convergence rate of the network achieving the goal of image denoising. The wavelet transform operation is adopted for the image to analyze the spatial characteristics of the image, the Doppler wave is used to scramble the high and low frequency coefficients of the image, the diffusion operation is used to calculate the adjacent area of the symmetrical points of the image, and the pixels to be diffused are arranged and combined according to the zero mean normalized cross-correlation score, so as to make the chaotic sequence have sufficient coupling correlation with the image and strengthen the image security. The mapping parameters are introduced into Logistic chaotic mapping, the random values of mapping variables are adjusted, the probability distribution function of chaotic system sequence is calculated, and the composite encryption of color image is completed. Simulation results show that the proposed method can effectively eliminate the pixel feature information of color image, and the encryption effect is good and feasible.

Key words: chaotic mapping,  , composite encryption,  , image denoising,  , wavelet analysis,  , scrambling transformatio