A novel multipurpose watermarking scheme capable of protecting and authenticating images with tamper detection and localisation abilities

Technologies that fall under the umbrella of Industry 4.0 can be classified into one of its four significant components: cyber-physical systems, the internet of things (IoT), on-demand availability of computer system resources, and cognitive computing. The success of this industrial revolution lies in how well these components can communicate with each other, and work together in finding the most optimised solution for an assigned task. It is achieved by sharing data collected from a network of sensors. This data is communicated via images, videos, and a variety of other signals, attracting unwanted attention of hackers. The protection of such data is therefore pivotal, as is maintaining its integrity. To this end, this paper proposes a novel image watermarking scheme with potential applications in Industry 4.0. The strategy presented is multipurpose; one such purpose is authenticating the transmitted image, another is curtailing the illegal distribution of the image by providing copyright protection. To this end, two new watermarking methods are introduced, one of which is for embedding the robust watermark, and the other is related to the fragile watermark. The robust watermark's embedding is achieved in the frequency domain, wherein the frequency coefficients are selected using a novel mean-based coefficient selection procedure. Subsequently, the selected coefficients are manipulated in equal proportion to embed the robust watermark. The fragile watermark's embedding is achieved in the spatial domain, wherein self-generated fragile watermark(s) is embedded by directly altering the pixel bits of the host image. The effective combination of two domains results in a hybrid scheme and attains the vital balance between the watermarking requirements of imperceptibility, security and capacity. Moreover, in the case of tampering, the proposed scheme not only authenticates and provides copyright protection to images but can also detect tampering and localise the tampered regions. An extensive evaluation of the proposed scheme on typical images has proven its superiority over existing state-of-the-art methods

A single watermark based scheme for both protection and authentication of identities

The security of a watermarking scheme is mainly categorised as either robust or fragile. The former can withstand an authorised alteration/attack, primarily used in copyright protection. The latter follows a zero tolerance towards any modification, used primarily in content authentication processes. The existing literature in the field projects that two separate watermarks are required to make a watermarking scheme robust and fragile, thus making the overall process cumbersome and complex. A novel image watermarking scheme that uses only one watermark while achieving both goals of copyright protection and authentication of identities is presented. An unconventional concept of checkpointing is introduced, which equips the proposed scheme to be either robust or fragile, making it superior in its application versatility. First, watermark embedding within the host/original image is achieved by a combination of transform domain techniques along with a novel median-based embedding block selection procedure. Second, checkpointing is performed in the spatial domain. The watermarked image in the absence of an attack is correlated to the one that is being attacked, using the template energy comparison-based approach. In the case of the robust watermark, such checkpointing can establish whether the carried out attack is authorised or not, determining the successful recovery of the watermark or vice-versa. Moreover, in the case of the fragile watermark, a sole confirmation of the occurrence of an attack is sufficient to make the watermark recovery impossible. Finally, the experimental analysis of the proposed scheme illustrates its excellent performance and superiority over state-of-the-art methods within the field

A dual watermarking scheme for identity protection

A novel dual watermarking scheme with potential applications in identity protection, media integrity maintenance and copyright protection in both electronic and printed media is presented. The proposed watermarking scheme uses the owner’s signature and fingerprint as watermarks through which the ownership and validity of the media can be proven and kept intact. To begin with, the proposed watermarking scheme is implemented on continuous-tone/greyscale images, and later extended to images achieved via multitoning, an advanced version of halftoning-based printing. The proposed watermark embedding is robust and imperceptible. Experimental simulations and evaluations of the proposed method show excellent results from both objective and subjective view-points

Significant difference-based watermarking in multitoned images

Digital multitoning is an advanced form of halftoning-based printing technique which renders multiple tones at each pixel of an image. This superior scheme delivers an improved print quality in terms of smooth texture, homogeneity and the suppression of artefacts. This Letter examines the potential scope of multitoning as an effective strategy to embed a binary watermark within a multitoned image. The proposed method uses the significant difference among the highpass wavelet coefficients achieved by discrete wavelet transform for watermark embedding. Furthermore, an improvised ordered dithering technique using adaptive threshold quantisation is also incorporated, which not only makes the proposed method time-efficient but also offers uniformity to the final image. The proposed watermarking technique is imperceptible and yields watermarked images with high peak signal-to-noise ratio value. Experimental simulations demonstrate that the proposed watermarking method is superior to the state-of-the-art methods in the context of both objective and subjective assessments

Detail and contrast enhancement for images using dithering based on complex wavelets

This paper introduces a new method for compensating the softening effects arising because of error diffusion based dithering. The proposed method is based on complex wavelet transforms (CWT) and has been named as complex wavelet based dithering. Similar to the wavelet based dithering, the proposed method emphasizes on details and contrast of an image. But, unlike wavelet based dithering it also provides better shift invariance and better directionality, resulting in better detail and contrast enhancement respectively. The proposed method compares favorably to two typical image dithering methods, namely, error diffusion and wavelet based dithering, in terms of the root mean square error and the peak signal to noise ratio

A novel signature watermarking scheme for identity protection

A novel non-blind watermarking technique for identity protection is presented. The proposed watermarking scheme uses the owner's signature as the watermark through which the ownership and validity of the document can be proven and kept intact. The proposed scheme is robust, imperceptible and faster in comparison to the other state of the art methods. Experimental simulations and evaluations of the proposed method show excellent results from both objective and subjective view points

A novel method to achieve ordered dithering in images

In this paper we propose a simple yet efficient way to achieve ordered dithering in images. The complex wavelet transform serves as the base of the proposed method, which makes it a multiscale approach. A traditional ordered dithering technique has also been incorporated, which not only provides uniformity to the final image but also makes the proposed method time efficient. The proposed method produces pleasant dithered images with a very strong emphasis on image details and enhances contrast. The proposed method outperforms the state of the art techniques from both objective and subjective point of views

Recent developments in halftone based image watermarking

In today's world, as the multimedia content is growing at an exponential rate, the security of multimedia content has become a very important issue. Nowadays, there are two major types of technologies which can provide solutions to the security problem. One is encryption and the other is watermarking. This paper presents a review on the recent trends of image watermarking with a focus on a special kind of watermarking method called halftone based image watermarking. The process of displaying an image with a lesser number of colours or grey levels is called halftoning. It is a crucial step in printing, especially when a printer can handle only a limited number of ink colours or grey levels

Contrast enhancement of dithered images using complex wavelets and novel amplification factors

Dithering creates an illusion of continuous tone output for a binary device. Error diffusion-based dithering or halftoning is an efficient technique that is primarily getting used in printing. In this paper error diffusion halftoning has been used to achieve image dithering based on complex wavelets. Similar to the wavelet-based dithering, Floyd-Steinberg error diffusion has been incorporated, but in addition a new set of sub band amplification factors is coined in the proposed method to further enhance the contrast in a dithered image. Experimental results show that the proposed method is superior to state-of-the-art methods in terms of subjective and objective assessments

Contrast enhancement using pixel based image fusion in wavelet domain

In this paper image fusion has been achieved using one of the existing state-of-the-art pixel based method in wavelet domain. In addition to this, a new technique for contrast enhancement has been incorporated that has been able to make the final fused image to look more crisp, sharp and clear from the perspective of the human visual system. Ultimately the existing method has been extended to the colored images as well which is first of its kind extension. The proposed technique has been able to improve a state-of-the-art practice in terms of subjective and objective assessments