With the increase in use of digital technology, use of data items in the format of text, image and videos are also increases. To securely send this data, many users and smart applications have adapted the image encryption approach. But the existing concepts are based on general AES approach. There is need to securely send the data with the addition of some expert image encryption and key generation approach. In this paper, we are using Matrix Array Symmetric Key (MASK) for the key generation and Chaos based approach for the image encryption. The main function of MASK is to generate the key for the encryption and decryption. The encryption process involves the generation of key. We have considered the key of MASK-256 for the encryption having 16 rounds. Chaos based concept has been considered for the encryption of image. Here, permutation- substitution based chaos based approach has been adopted for the image encryption. Moreover, in this approach, we have adapted the concept of partial encryption of image pixels instead of complete encryption so that in case of arrack, intruder can be confused with the partial encrypted image. In this approach, different image samples having different sizes have been considered. Further, concept is evaluated based on the parameters of Information Entropy, Elapsed Time, Precision, Recall and F-Measure.