Abstract This paper proposed a quckly image encrypting algorithm based on ridgelet transformation and chaos sequence. Firstly， the secret image was scrambled. Secondly， the secret image and the chaotic image generated by extended chaotic sequence were decomposed into low-frequency and high-frequency images， then the ridgelet coefficients were calculated， the fused ridgelet coefficients were composed， and the fusion image was got by inverse ridgelet transformation. Finally， the performance of the fusion algorithm was evaluated and analysed. The experimental results show that the proposed method is simple and viable．
