Watermarking of Digital Images With the Substitution of Low-Value Bits to Increase Capacity

Watermarking of Digital Images With the Substitution of Low-Value Bits to Increase Capacity

Aliasghar Erfannia (Department of Computer Science, Khoy Branch, Islamic Azad University, Khoy, Iran), Abdolreza Hatamlou (Department of Computer Science, Khoy Branch, Islamic Azad University, Khoy, Iran) and Farzaneh Mahalleh (Department of Computer, Faculty of Khoy, West Azarbijan Branch, Technical and Vocational University (TVU), Khoy, Iran)
Copyright: © 2017 |Pages: 10
DOI: 10.4018/IJCVIP.2017100104
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Abstract

In this article, a novel watermarking method is proposed which applies the substitution of LSB for low-value parts of the image to embed confidential data. The watermark bits are encoded before being placed. Also, the data on the diameters of the host image blocks are selected on the basis of an irregular determined algorithm that is resistant to attacks. The host image applied in the proposed algorithm should be grayscale. The proposed algorithm uses three bits to embed data that will increase the capacity. In the conventional LSB method, in host image matrix, data are stored in the consecutive numbers, but in this proposed scheme, the host image blocks are divided into separate n × n parts and the diameter of each block are placed in a vector. Then embedded watermarking bits in a vector of numbers is done, from the resulting vector a new block is created, and finally, that block is stored in a new matrix. Then the host image block is overwritten which results in a watermarked image with high capacity.
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2. Literature Review

In the visible watermarking, usually transparent watermarked image is produced by adding weight to the edges in an image below watermarking signal is properly preserved. Mintzer et al. (1997) presented a reversible watermarking model image that watermarked image on the host image is visible and the original image can be retrieved. Also, Jung Jin et al. in (2006) presented a visible watermarking method for image authentication that is fully transferable and replaceable. This model is particularly useful for military or medical images. The reversible, visible watermarking method in Yongjian et al. (2006) is a technique based on user key that is applied on visible watermarking signal on human visual system (HVS) to produce visible watermarked image. A user-key method allows authorized users to retrieve high-quality images, while unauthorized users are foreclosed. Shocky et al. in (2006) provided a visible watermarking method using two mapping algorithms: pixel value mapping algorithm (PVMA) and pixel switching algorithm (PPSA). In their method, the pixels are processed by PVMA, and by the PPSA the visible watermarked pixel is formed. By using reverse PPSA and reverse PVMA on watermarked image, the original image is retrieved. In this method for more security random number is added to the watermarking pixels.

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