In this paper, QR bar code and image processing techniques are used to construct a nested steganography scheme. There are two types of secret data (lossless and lossy) embedded into a cover image. The lossless data is text that is first encoded by the QR barcode; its data does not have any distortion when comparing with the extracted data and original data. The lossy data is a kind of image; the face image is suitable for our case. Because the extracted text is lossless, the error correction rate of QR encoding must be carefully designed. We found a 25% error correction rate is suitable for our goal. In image embedding, because it can sustain minor perceptible distortion, we thus adopted the lower nibble byte discard of the face image to reduce the secret data. When the image is extracted, we use a median filter to filter out the noise and obtain a smoother image quality. After simulation, it is evident that our scheme is robust to JPEG attacks. Compared to other steganography schemes, our proposed method has three advantages: (i) the nested scheme is an enhanced security system never previously developed; (ii) our scheme can conceal lossless and lossy secret data into a cover image simultaneously; and (iii) the QR barcode used as secret data can widely extend this method's application fields.
