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An imperceptible visible watermarking (IVW) algorithm is proposed to deliver auxiliary information about the visual contents, including ownership information. The proposed algorithm overcomes several inconveniences presented in previously reported IVW algorithms using the just noticeable difference (JND) criterion, invisible watermarking and binarisation function. The proposed algorithm consists of the visible watermark embedding and the exhibition stages. The JND criterion is used to embed visible watermark pattern in an imperceptible manner by the human visual system, while invisible watermarking based on the discrete cosine transform is used to share crucial parameters between both stages, which makes possible the watermark visualisation without any side information. In the watermark exhibition stage, the imperceptibly embedded visible watermark pattern is exhibited by the binarisation function. The proposed algorithm can be applied to any class of images with different characteristics and several visible watermark patterns can be embedded into an input image. Evaluation results show that performance of the proposed algorithm is better compared with previously reported algorithms from several practical points of view. [ABSTRACT FROM AUTHOR]

The development of coding schemes with the capacity to simultaneously encrypt and compress audio signals is a subject of active research because of the increasing necessity for transmitting sensitive audio information over insecure communication channels. Thus, several schemes have been developed; firstly, some of them compress the digital information and subsequently encrypt the resulting information. These schemas efficiently compress and encrypt the information. However, they may compromise the information as it can be accessed before encryption. To overcome this problem, a compressing sensing-based system to simultaneously compress and encrypt audio signals is proposed in which the audio signal is segmented in frames of 1024 samples and transformed into a sparse frame using the discrete cosine transform (DCT). Each frame is then multiplied by a different sensing matrix generated using the chaotic mixing scheme. This fact allows that the proposed scheme satisfies the extended Wyner secrecy (EWS) criterion. The evaluation results obtained using several genres of audio signals show that the proposed system allows to simultaneously compress and encrypt audio signals, satisfying the EWS criterion. [ABSTRACT FROM AUTHOR]