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Aiming at the identification of natural images and computer generated graphics, an image source pipeline forensics method based on binary similarity measures of PRNU (photo response non-uniformity) is proposed. As PRNU is a unique attribute of natural images, binary similarity measures of PRNU are used to represent the differences between natural images and computer generated graphics. Binary Kullback-Leibler distance, binary minimum histogram distance, binary absolute histogram distance and binary mutual entropy are calculated from PRNU in RGB three channels. With a total of 36 dimensions of features, LIBSVM is used for classification. Experimental results and analysis indicate that it can achieve an average identification accuracy of 99.83%, and the capability of identifying natural images and computer generated graphics is balanced. Meanwhile, it is robust against JPEG compression, rotation and additive noise. [ABSTRACT FROM AUTHOR]

Aiming at the problem of image tampering, a novel detection method is proposed based on the image noise and lacunarity. As there exist differences in image sensor pattern noise and image lacunarity between real image and tampered image, standard deviation of noise, relative frequency lacunarity (RFL), relative frequency mean (RFM) and relative frequency variance (RFV) are extracted from the suspected image to construct feature space. By using LIBSVM classifier, the image is detected if it is tampered or not. Experimental results and analysis show that it can effectively be used for the detection of real image and tampered image, natural image and computer generated graphics. Furthermore, it can be implemented for the detection of artificial blurring in the image with high precision. [ABSTRACT FROM AUTHOR]

To discriminate the acquisition pipelines of digital images, a novel scheme for the identification of natural images and computer-generated graphics is proposed based on statistical and textural features. First, the differences between them are investigated from the view of statistics and texture, and 31 dimensions of feature are acquired for identification. Then, LIBSVM is used for the classification. Finally, the experimental results are presented. The results show that it can achieve an identification accuracy of 97.89% for computer-generated graphics, and an identification accuracy of 97.75% for natural images. The analyses also demonstrate the proposed method has excellent performance, compared with some existing methods based only on statistical features or other features. The method has a great potential to be implemented for the identification of natural images and computer-generated graphics. [ABSTRACT FROM AUTHOR]

Based on the principle of predation using spider web, a novel semi-blind and semi-fragile reversible watermarking scheme for authenticating 2D vector graphics is proposed. Aiming to resolve the problem of the deficiency in robustness resulting from watermark embedding in file stream order, this scheme proposes to embed geometric correlated watermark by adding vertices for entities. Firstly, two spider webs are generated based on the convex hull of 2D vector graphics and a secret key. Secondly, let the first spider web intersect with the 2D vector graphics, and some vertices are added at the intersections. After that, let the second spider web intersect with the 2D vector graphics, and record the number of intersections between every cobweb and entities. The authentication is carried out by checking the intersection states and the number of intersections between the 2D vector graphics and two spider webs. Experimental results and analysis show that it can localize the tampers in entity with the premise that the convex hull is kept. Meanwhile, the watermarking can keep the shape of 2D vector graphics, and it is robust against translation, scaling, rotation and even entity rearrangement. It provides a novel means for the content protection of 2D vector graphics. [ABSTRACT FROM AUTHOR]

The aim of the work presented in this paper is to discriminate natural images (NI) and computer generated graphics (CG). The texture differences are analyzed to the residual images of NI and CG. The residual images are first extracted by using multiple linear regressions, and then the fitting degree of the regression model is investigated. Through the analysis of the difference of their residual images, 9 dimensions of histogram features and 9 dimensions of multi-fractal spectrum features are extracted to represent their texture differences. Combined with 6 dimensions of regression model fitness features, natural images and computer generated graphics are discriminated by using a support vector machine (SVM) classifier. Experimental results and analysis show that it can achieve an average identification accuracy of 98.69%, and it is robust against JPEG compression, rotation, additive noise and image resizing. Compared with some existed methods, the selection of features is effective and fewer features are required for representing the differences between NI and CG. Meanwhile, the classification time is significantly reduced and the robustness is maintained. It has great potential to be used in image source pipeline identification. [ABSTRACT FROM AUTHOR]

Abstract: According to the characteristics of the coordinates and phases in 2D CAD engineering graphics, difference histograms are constructed. Consequently, two reversible watermarking schemes based on difference histogram shifting are put forward. The first scheme HS_C implements the integer part of coordinate values to construct the adjacent difference histogram and hides messages in the peak and zero point pairs. The scheme can achieve high capacity and good invisibility in the graphics with high correlated coordinates. Instead of coordinates, the second scheme HS_P adopts the integer part of the phase value as the cover data, and the watermark is embedded by shifting and modifying the difference histogram of the phase. It is robust against translation, rotation and even scaling. Experimental results show that both schemes are strictly reversible. The proposed schemes have great potential to be applied for content authentication or secret communication of 2D CAD engineering graphics. [Copyright &y& Elsevier]

Abstract: Copyright violation and illegal manipulation of digital data have been acute challenges for many sectors since the very same set of enabling techniques for generating and processing digital data started to emerge. Although traditional protective methods, such as encryption and digital signatures, have been in use for decades, their inability to provide protection after decryption and locating tampering has prompted the development of digital watermarking. In this paper, a semi-fragile watermarking algorithm for authenticating 2D CAD engineering graphics based on log-polar coordinate mapping is proposed. Firstly, the vertices are divided into groups, and for each group, the vertices for carrying a watermark are mapped to the log-polar coordinate system. Then the watermark is embedded in the mantissa of the real-valued log-polar coordinates via bit substitution. Theoretical analysis and experimental results show that the proposed algorithm is not only robust against incidental global operations such as rotation, translation and scaling, but can also detect and locate malicious attacks such as entity modification and entity addition/deletion. [ABSTRACT FROM AUTHOR]