High Hiding Rate Image Steganography System Based On Affine Transform and LSB Method.

The spying and intrusion operation had been widely spread to steal the information especially with the development of computer networks (like,Internet). To prevent this danger the development of a new technology called “digital information hiding” was developed in such a way that the intruder cannot notice the existence of secret information in the media.In this project an image steganograph system is introduced. The proposed system is based on using the affine transform to represent the blocks of the secret image in terms of the blocks of the cover image. Then, the least significant bits (LSB) insertion method is utilized to hide the quantized affine transform coefficients of the secret image in the cover image. Also in this research some block indexing methods are utilized to improve (i.e, speed up) the involved trials of affine mappings. Three systems (they are traditional IFS, IFS with symmetry predictions, and IFS with symmetry prediction and blocks indexing) have been established. They used to manage the way of selecting the suitable domain (cover) to represent the range (secret) block. The domain search operation will not need to make all isometric-block tests on each domain block. The best domain isometric state
is assessed using the introduced isometric predictor; which is based on the moment status of the matched block. This will significantly reduce the matching time because only one match, instead of eight, will be tested to evaluate the IFS-similarity between any range and domain block. Also, a block indexing method is introduced to filter the domain blocks, and filter-in only those domain blocks that have similar block index with that of the mapped range block to be tested using IFS-matching. Some of the well known fidelity measures (like, MSE and PSNR) have been used to asses the quality of the reconstructed image. The conducted test results indicated that the proposed improvements have reduced the required hiding time down to 6.81 second (around 80 times in comparison with the traditional scheme) without making significant degradation in image quality.