Watermarking is the process that embeds data called a watermark, a tag, or a label into a multimedia object, such as images, video, or text, for their copyright protection. According to human perception, the digital watermarks can either be visible or invisible. A visible watermark is a secondary translucent image overlaid into the primary image and appears visible to a viewer on a careful inspection. The invisible watermark is embedded in such a way that the modifications made to the pixel value is perceptually not noticed, and it can be recovered only with an appropriate decoding mechanism. This project presents a new very large scale integration (VLSI) architecture for implementing two visible digital image watermarking schemes. The proposed architecture is designed to aim at easy integration into any existing digital camera framework.
Two fundamental operations performed by a digital camera are image capturing and storing. The images are subsequently transmitted in various forms over appropriate media. These images are always vulnerable to various forms of copyright attacks and ownership issues. This paper introduces a digital camera with built-in copyright protection and security mechanism for images produced by it. Since the proposal of the trustworthy digital camera, significant research has been done in developing algorithms for watermarking and encryption with the aim of using them in digital cameras. However, only few of these efforts are involved with the architectural development of the entire digital camera. Incorporation of encryption and watermarking together in the digital camera will assist in protecting and authenticating image files.In this work, architecture and a hardware efficient FPGA based watermark module towards the development of the complete digital camera.
WATERMARKING is the process that embeds data called awatermark, a tag, or label into a multimedia object such that the watermark can be detected or extracted later to make an assertion about the object. The object may be an image, audio, video, or text [1]. Whether the host data is in spatial domain, discrete cosine-transformed, or wavelet-transformed, watermarks of varying degree of visibility are added to present media as a guarantee of authenticity, ownership, source, and copyright protection. In general, any watermarking scheme (algorithm) consists of three parts, such as the following:
1) watermark;
2) encoder (insertion algorithm);
3) decoder and comparator (verification or extraction or detection algorithm)
Whether each owner has a unique watermark or an owner wants to use different watermarks in different objects, the marking algorithm incorporates the watermark into the object. The verification algorithm authenticates the object determining both the owner and the integrity of the object. Watermarks and watermarking techniques can be divided into various categories. The watermarks can be applied either in spatial domain or in frequency domain. It has been pointed out that the frequency-domain methods are more robust than the spatial-domain techniques. On the other hand, the spatialdomain watermarking schemes have less computational overhead compared with frequency-domain schemes. According to human perception, the digital watermarks can be divided into four categories:
1) visible;
2) invisible-robust;
3) invisible-fragile;
4) dual
A visible watermark is a secondary translucent image overlaid into the primary image and appears visible to a casual viewer on careful inspection. The invisible-robust watermark is embedded in such a way that modifications made to the pixel value is perceptually not noticed, and it can be recovered only with appropriate decoding mechanism. The invisible-fragile watermark is embedded in such a way that any manipulation or modification of the image would alter or destroy the watermark. A dual watermark is a combination of a visible and an invisible watermark . In this type of watermark, an invisible watermark is used as a back-up for the visible watermark. There are numerous software-based watermarking schemes available in literature. A vast research community involving experts from computer science, cryptography, signal processing, and communications, etc., are working together to develop watermarks that can withstand different possible forms of attacks, each one of which has its own applications and thus is equally important. There is a gap between the image capture and image transmission in thewaywatermarking is used presently. Once the images are acquired,watermarks are inserted in them offline, and then images are made available. The objective of this research work is to implement hardware-based watermarking schemes so as to bridge that gap. The watermark chip will be fitted in the devices that acquire the image and watermark the images in real time while capturing.
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