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2L-DWTS — Steganography technique based on second level DWT

Steganography is a technique used to communicate a secret message secretly hidden in an innocuous cover. In this paper, a new image steganography technique 2L-DWTS is proposed. This technique, 2L-DWTS embeds secret message in the higher frequency components among the second level DWT components of the cover image. Coefficients in the low frequency components (LL), at both DWT levels, are left untouched improving the image quality. The stego images obtained using 2L-DWTS are very similar to the corresponding cover images, thereby making this technique secure. The message of size as big as 28.12% of the cover image size can be embedded using this technique. The extraction method does not need the original cover image or any separate key for extracting the message. The experiments conducted on monochrome as well as colored BMP and JPEG images show that using this technique a high capacity, secure, less perceptible stego image is formed. Various metrics - MSE, PSNR, NC, NCC, NAE and IF are used to establish this fact.