A joint of image encryption and compression is investigated, and a novel joint encryption and compression scheme is proposed. In our scheme, the encryption process is performed before compression. Making use of the properties of discrete wavelet transform (DWT) and Set Partitioning in Hierarchical Trees (SPIHT) coding, confusion is restricted to the interior of single subband image itself and so image details are retained. Furthermore, diffusion preserves the two most significant bits (MSBs) and the sign bit, which contain important information about the image. The experiments show that the proposed algorithm possesses a good visual quality of the reconstructed image and a high encryption speed.