Variable length encoding in multiple frequency domain steganography

In this paper a multiple frequency domain steganography is proposed; it uses DWT (discrete wavelets transform) with DCT (discrete cosine transform) techniques, which are applied sequentially on the cover image. Embedding the secret message is done in the high frequency coefficients to provide a high imperceptibility; as it is the most important property of any steganography system. For secret message encoding, variable length encoding is used with a special character codes to encode the characters into binary data. This encoding encrypts the secret message and reduces the number of bits used to encode each character, which results in the increment of the capacity. With this new technique, we got very good results through satisfying and improving the most important properties of steganography such as: Imperceptibility; improved by having the MSE (mean square error) → 0 and PSNR (peak signal to noise ratio) → 128 db, security; improved by using an encrypted Stego-key and secret message by the encoding, capacity; improved by encoding the secret message characters with variable length codes and embedding the secret message in the YCbCr components instead of the RGB.