Halftone Image Watermarking Research Articles

Halftone Image Watermarking by Content Aware Double-Sided Embedding Error Diffusion.

In this paper, we carry out a performance analysis from a probabilistic perspective to introduce the error diffusion-based halftone visual watermarking (EDHVW) methods' expected performances and limitations. Then, we propose a new general EDHVW method, content aware double-sided embedding error diffusion (CaDEED), via considering the expected watermark decoding performance with specific content of the cover images and watermark, different noise tolerance abilities of various cover image content, and the different importance levels of every pixel (when being perceived) in the secret pattern (watermark). To demonstrate the effectiveness of CaDEED, we propose CaDEED with expectation constraint (CaDEED-EC) and CaDEED-noise visibility function (NVF) and importance factor (IF) (CaDEED-N&I). Specifically, we build CaDEED-EC by only considering the expected performances of specific cover images and watermark. By adopting the NVF and proposing the IF to assign weights to every embedding location and watermark pixel, respectively, we build the specific method CaDEED-N&I. In the experiments, we select the optimal parameters for NVF and IF via extensive experiments. In both the numerical and visual comparisons, the experimental results demonstrate the superiority of our proposed work.

Halftone image watermarking via optimization

Although halftone image watermarking technologies have been rapidly developing in the 21st century, the existing techniques lack a theoretical basis. In this paper, we tackle halftone image watermarking problems from a theoretical perspective. First, we propose a general optimization framework for Halftone Visual Watermarking (HVW), which is a certain category of halftone image watermarking techniques. Then two specific HVW problems, Single-sided Embedding Error Diffusion (SEED) and Double-sided Embedding Error Diffusion (DEED) are presented and solved by applying the proposed framework. With SEED and DEED obtained, both the theoretical solutions and experimental results indicate that our previous heuristic methods, Data Hiding by Conjugate Error Diffusion (DHCED) and Data Hiding by Dual Conjugate Error Diffusion (DHDCED), are special cases of SEED and DEED, respectively. We also demonstrate that DEED can achieve outstanding performance compared to DHDCED and other previous methods by selecting different parameters. With this paper, we essentially build a bridge between the theory and practical implementations of HVW problems.

Watermark Embedding for Multiscale Error Diffused Halftone Images by Adopting Visual Cryptography

Error Diffusion has been widely adopted in the printing industry due to its good visual quality and simple implementation. However, error diffusion still possesses its own deficiencies. Thus multiscale error diffusion (MED) has been developed, and this method outperforms traditional error diffusion according to extensive research results. The majority of previous halftone image watermarking techniques cannot be directly applied to MED halftone images. Since there is no halftone visual watermarking (HVW) method for MED halftone images in existing methods, we propose the first HVW method for MED halftone images, Copyright Protecting Multiscale Error Diffusion (CoP-MED), in this paper. By adopting the visual cryptography principle, CoP-MED can effectively embed a secret pattern into two MED halftone images, where the secret pattern can be decoded clearly by simply overlaying the two stego halftone images or performing not-exclusive-or operation between them. Parameter selection is also discussed based on the experimental results. Later, in comparison tests, CoP-MED shows superior performance compared to existing works.

Anti-Counterfeit Technology of Halftone Image Watermarking by Digital Screening

From the point of view of the digital printing, this paper focused on researching the anti-counterfeit print technology of halftone images and directly detecting techniques combined with digital image processing technology, thereby enhancing the security features of the printed mater. The grating has converged effect on light in the corresponding direction, which makes it compress and isolate images. According to this feature of grating, the variable angle algorithm of screening anti-counterfeit technology was proposed, and in accordance with the algorithm, the experiment of grating extracting the watermarking of halftone image was studied in this paper. In this experiment, we designed other screening angles to hide the information, we called it the variable angle screening security technology. When detecting the hidden information, only at the same angle could we observe the security effect with corresponding lines of the grating. The experimental results showed that the variable angle algorithm of screening anti-counterfeit technology had nice security effect, and could be used in practical application. DOI: http://dx.doi.org/10.11591/telkomnika.v11i9.3252

The Halftone Image Watermarking Algorithm Based on Error Diffusion

Halftone image watermarking is an important direction of research and application in the field of information hiding now. This paper proposed a halftone image watermarking algorithm based on error diffusion. It is an effective measure to copyright protection of printed matter, source authentication and prevented forgery etc. This algorithm embedded watermarking image information as an error signal into the pixels adjacent to this location by error diffusion algorithm. Information embedding was completed synchronously with halftone. So watermarking extraction is simple and fast. Experiments show that this algorithm can embed a binary watermarking image into the halftone image with the same size. This algorithm has a good performance in resistance to a variety of attacks (such as noise jamming, fouling, and rotation etc.).So it has certain practical value.

A Novel Scrambling Algorithm for Bio-Data Hiding Technique

In this paper we will overview the use of data hiding techniques in digital images. In particular we will describe how one can use steganography to hide biometric information in a digital image. This proposed technique proposes a quite simple solution for inserting a secure authentication watermarking in dispersed-dot halftone images. This technique explain how, the hidden biometric data are extracted accurately from the carrier image using a secret key and describe how it can be applied to any kind of binary images including clustered-dot halftones. Furthermore, this technique explains how data are hidden in the host image in an adaptive way to minimize possible degradations to that image. The proposed technique not only provides a better way for embedding large amounts of data into cover images with imperceptions, but also offers an easy way to accomplish secrecy. This method provides better results as compared to LSB replacement method where the distortions are spread all over the image.

Oriented Modulation for Watermarking in Direct Binary Search Halftone Images

In this paper, a halftoning-based watermarking method is presented. This method enables high pixel-depth watermark embedding, while maintaining high image quality. This technique is capable of embedding watermarks with pixel depths up to 3 bits without causing prominent degradation to the image quality. To achieve high image quality, the parallel oriented high-efficient direct binary search (DBS) halftoning is selected to be integrated with the proposed orientation modulation (OM) method. The OM method utilizes different halftone texture orientations to carry different watermark data. In the decoder, the least-mean-square-trained filters are applied for feature extraction from watermarked images in the frequency domain, and the naïve Bayes classifier is used to analyze the extracted features and ultimately to decode the watermark data. Experimental results show that the DBS-based OM encoding method maintains a high degree of image quality and realizes the processing efficiency and robustness to be adapted in printing applications.

Halftone Image Watermarking based on Visual Cryptography

In this paper we have proposed digital watermarking scheme for halftone images based on visual cryptography scheme. The scheme does not embed the watermark directly on the halftone image instead watermark will be divided into the parts called as shares. The scheme not only protects the watermark but also provides an effective copyright protection scheme. At the time of watermark embedding verification share is generated and at the time of watermark extraction master share is generated using (2, 2) visual cryptography scheme. Verification share and master share are used to extract the watermark pattern. The experimental results show that the scheme is robust and transparent against various watermarking attack. General Terms Cryptography, digital image processing.

Watermarking in halftone images with noise balance strategy

AbstractTwo novel and robust methods for embedding watermarks into error‐diffused halftone images are presented in this study. The first method is referred to as Dither‐Referenced Error Diffusion (DREDF), where the proposed Average Ordered Dithering (AOD) is adopted to produce the referenced halftone image. The Noise‐ Balanced Error diffusion (NBEDF) is then applied to embed the watermark. The other method is referred to as Parity‐Matched Error Diffusion (PMEDF). This approach achieves good image quality and capacity as high as 6.25 to 25%. Since the two techniques are blind, the decoder does not need any priori knowledge of the original halftone image or watermark. The capacity of the two approaches is also flexible to accommodate all kinds of applications. As the experimental results demonstrated, both techniques are able to guard against degradation due to cropping, tampering, and the print‐and‐scan process in error‐diffused halftone images. Moreover, both methods have features of low computational complexity, low memory demand, and good image quality. © 2010 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 20, 202–214, 2010.

Watermarking in halftone images with parity-matched error diffusion

In this paper, a halftone watermarking technique of high watermark rate, robustness, and watermark-rate flexibility is presented. This technique, namely the parity-matched error diffusion (PMEDF) method, is capable of achieving an embedded watermark rate as high as 6.25–25% with good image quality and without the need for the original image as the reference for the decoding. The proposed PMEDF method employs the high efficient parity-matching strategy to spread a watermark bit to each pixel of a block of the host image. Thus, the majority voting mechanism can be applied for decoding to achieve an advantage of high robustness. As documented in the experimental results, this technique is capable of guarding against degradation, due to cropping, tampering, as well as print-and-scan process in error-diffused halftone images.

Watermarking in halftone images with mixed halftone techniques

AbstractOrdered dithering and error diffusion are the two most popular processes to produce halftone results for printing industry. Ordered dithering inherently has the benefit of efficiency. On the other hand, error diffusion has high quality and reasonable complexity. In this article, we propose a watermarking that adopts the ordered dithering to produce the referenced halftone image, then applying the noise‐balanced error diffusion to embed the watermark. A low computational complexity, low memory demand, and good embedded image quality are achieved with the proposed technique. From the experimental results, this technique can guard against the cropping and print‐and‐scan two major degradation processes in halftone images. © 2008 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 17, 303–314, 2007

Look-up Table Based Reversible Data Hiding for Error Diffused Halftone Images

This paper proposes a reversible data hiding method for error diffused halftone images. It employs statistics feature of pixel block patterns to embed data, and utilizes the HVS characteristics to reduce the introduced visual distortion. The watermarked halftone image can be perfectly recovered if it is intact, only a secret key is required. The method is suitable for the applications where the content accuracy of the original halftone image must be guaranteed, and it is easily extended to the field of halftone image authentication.

Hybrid pixel-based data hiding and block-based watermarking for error-diffused halftone images

A low computational complexity noise-balanced error diffusion (NBEDF) technique is proposed for embedding watermarks into error-diffused images. The visual decoding pattern can be perceived when two or more similar NBEDF images are overlaid, even in a high activity region. Also, with the modified improved version of NBEDF, two halftone images can be made from two totally different gray-tone images, and still provide a clear and sharp visual decoding pattern. With self-decoding techniques, we can also decode the pattern with only one NBEDF image. However, the NBEDF method is not so robust to damage due to printing or other distortions. Thus, a kernels-alternated error diffusion (KAEDF) technique is proposed. By using them alternately in the halftone process, we find that two well-known kernels (Jarvis, J.F. et al., 1976; Stucki, P., 1981) are compatible. In the decoder, because the spectral distributions of Jarvis and Stucki kernels are different in the 2D fast Fourier transform domain, we use the cumulative squared Euclidean distance criterion to determine each cell in a watermarked halftone image belonging to either Jarvis or Stucki, and then decode the watermark. Furthermore, because the detailed textures of Jarvis and Stucki patterns are somewhat different in the spatial domain, the lookup table (LUT) technique is also used for fast decoding. From simulation results, the correct decoding rates for both techniques are high and extremely robust, even after printing and scanning processes. Finally, we extend the hybrid NBEDF and KAEDF algorithms to two color EDF halftone images, where 8 independent KAEDF watermarks and 16 NBEDF watermarks can be inserted and still achieve a high-quality result.

Steganography in halftone images: conjugate error diffusion

In this paper, we propose a method called data hiding by conjugate error diffusion (DHCED) to hide an invisible binary visual pattern in two or more error diffused halftone images, which can be from the same or different multi-tone images. In DHCED, distortions of limited magnitude are added to the multi-tone image such that the pixel values of the various halftone images tend to be conjugate to each other. With the conjugate relationship, the dark regions of the hidden pattern would appear on the halftone images when they are overlaid. Simulation results show that the DHCED watermarked halftone images have good visual quality, and the hidden pattern is revealed with good contrast when the watermarked halftone images are overlaid. Even better contrast can be achieved when more than two watermarked halftone images are used.