The widely use of data digitization leads to the necessity of hiding the content of a message when it enters an insecure channel. The message prepared by the sender is encrypted before transmission. The encryption process requires an encryption algorithm and a key. In image cryptography, recently numbers of effective chaos-based image encryption schemes have been proposed. This paper presents a novel image encryption scheme which encrypts the pixels' RGB component instead of the pixels itself, where every pixel in the image will be extracted to its RGB triple, encrypted, and prepared to be transmitted. In the encryption process we use another image as a key, this image should be larger than or of the same size of the plain image that we intend to encrypt. The image encryption scheme introduced is based on chaotic systems. Simulation results show that the proposed image encryption scheme achieves high level of security, and reduces the encryption and the decryption time of image data.