Applying Encryption Method to Color FlC


In this paper a simple and fast algorithm that used XOR function to encrypt color images compressed with a fast fractal image compression (FFIC)was used. The algorithm first included converting the image from the RGB color space into the YIQ color space and each band was treated separately. Main difficulty with fractal coding method is that it takes long time to compress single image. The FIC is speeded up by filtration of the domain pool blocks using the centralized moments coefficients which are applied to each of range and domain blocks. Another speeding is applied by using these descriptors to determine the suitable symmetry case reducing the eight isometric trails to one trail. After finding the fractal coefficients for the best matching, two of the fractal coefficient are encrypted using XOR operation. The first key encryption is used to generate an array of sequenced numbers with an increase depending on the key, and length of the array is equal to the number of the range blocks, this key is used to encrypt the average coefficients. The symmetry coefficients are encrypted by another key. Then quantization, deferential pulse code modulation(DPCM) process are applied to each of the fractal coefficient. The decryption procedure is similar to that of the encryption but in the reversed order. The proposed method provided fast, good compression ratio (CR), secure image and good quality for the reconstructed image after decompression and decryption process.