Steganography is the technique for hiding secret information in other data such as multimedia images, text, audio. For hiding secret information in images, there exist a large variety of steganographic techniques some are more complex than others and all of them have respective strong and weak points. The existing methods hide the information using constant bit length in integer wavelet coefficients. The main drawback of the existed methods is overflow of pixels may occur in integer wavelet domain after embedding. This may probably results bit error while recovering secret information. This paper uses variable bit length based on float wavelet coefficients to hide the data in a particular positions using secret key and Optimal Coefficients Adjustment Process (OCAP). The system combines an float wavelet transform and the variable rate of embedding and embeds secret data in a random order using a secret key only known to both sender and receiver to maximize performance of this steganographic method. to obtain an optimal mapping function to reduce the difference error between original coefficients values and modified values, OCAP algorithm is proposed. From the experimental results it is seen that the proposed methods achieve a much higher visual quality as indicated by the high psnr in spite of hiding a larger number of secret bits in the image. Moreover, extraction of the secret information is independent of original cover image.

Steganography float wavelet coefficients variable rate psnr OCAP