In a JPEG decoder, the quantized discrete cosine transform (DCT) coefficient blocks are usually processed using the inverse DCT to reconstruct an approximation of the original image. In the presence of quantization of...
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In a JPEG decoder, the quantized discrete cosine transform (DCT) coefficient blocks are usually processed using the inverse DCT to reconstruct an approximation of the original image. In the presence of quantization of the transform coefficients, the use of the inverse DCT in the decoder is not the best choice: We propose a procedure to design a family of separable 2D synthesis filters that minimize the reconstruction error power and these filters are used in the decoder instead of the inverse DCT. The appropriate reconstruction filters are selected on the basis of the standard quantization information provided in the JPEG bit stream. We show that the proposed decoding method gives some gain with respect to the standard decoder, making use of only the information provided by the JPEG bit stream.
If visual information retrieval should make further progress, it will be necessary to identify new ways to derive visual properties from higher levels of understanding than the pixel level (e.g. from low-level feature...
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If visual information retrieval should make further progress, it will be necessary to identify new ways to derive visual properties from higher levels of understanding than the pixel level (e.g. from low-level features). The paper outlines the implementation of modelling of feature hierarchies in the visual information retrieval framework VizIR (free under GPL). The approach allows for the derivation of high-level features from low-level features by aggregation and localisation as well as semantic enrichment with additional knowledge. The technical implementation is based on the MPEG-7 structures for aggregation and specialisation.
The massive information-sharing capabilities and global reach of Facebook are of great interest to organizations of all types, including those with malicious and/or illegal intents. Our main findings in this research ...
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The massive information-sharing capabilities and global reach of Facebook are of great interest to organizations of all types, including those with malicious and/or illegal intents. Our main findings in this research include the following. Steganography can be employed to send covert information via Facebook photos and potentially videos as well. Facebook Cover Photos can effectively utilize steganography, of at least 15.75% capacity using DCT coefficient embedding algorithms. Network traffic analysis determined no distinguishable differences between network traffic patterns of normal images and cover photos as they were uploaded to the Facebook servers. Firewall rules can be written to block all image uploads to Facebook.
Real time implementation of wavelet transformations is becoming of great importance, since it is one of the key elements of JPEG2000 and MPEG4 encoding operations. This paper details a dedicated wavelet decomposition ...
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Real time implementation of wavelet transformations is becoming of great importance, since it is one of the key elements of JPEG2000 and MPEG4 encoding operations. This paper details a dedicated wavelet decomposition implementation for ADSP-BF533 and ADSP-BF561 fixed-point DSPs, and reports experimental results on several test images.
MPEG (Moving Pictures Expert Group) is an industrial standard for video processing and is widely used in multimedia applications in the Internet. However, no security provision is specified in the standard. We conduct...
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MPEG (Moving Pictures Expert Group) is an industrial standard for video processing and is widely used in multimedia applications in the Internet. However, no security provision is specified in the standard. We conducted an experimental study of previously proposed selective encryption schemes for MPEG video security. This study showed that these methods are inadequate for sensitive applications. We discuss the tradeoffs between levels of security and computational and compression efficiency.
In this paper, a new watermarking method is presented to embed a binary watermark into an image. The proposed method uses a special type of fractal coding that its parameters are contrast scaling and the mean of range...
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ISBN:
(纸本)9781424437740
In this paper, a new watermarking method is presented to embed a binary watermark into an image. The proposed method uses a special type of fractal coding that its parameters are contrast scaling and the mean of range block. Also, it utilizes the fuzzy C-mean clustering to address the watermark bits. The experimental results show that the proposed method has high robustness against signal distortion such as JPEG compression, median filter and additive noise.
For image content authentication, a secure watermarking method using quantization-based embedding on the largest singular value (SV) is proposed. The block-wise quantization-based embedding can be vulnerable to vector...
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ISBN:
(纸本)0780388747
For image content authentication, a secure watermarking method using quantization-based embedding on the largest singular value (SV) is proposed. The block-wise quantization-based embedding can be vulnerable to vector quantization (VQ) attack and attacks associated with histogram analysis. To overcome these security problems, the proposed method places interdependency among image blocks and dithers the quantized value. By adjusting the threshold of the detector, a trade-off between the robustness to JPEG compression and the probability of misdetection can be made. The proposed method can detect a tampered area with high sensitivity. This is confirmed by experimental results and security analysis.
Image manipulation represents a true “art”, which takes into account the images with a lot of their properties. There are many ways a digital photo can be manipulated, so the forger can use one or more combinations ...
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ISBN:
(纸本)9781538649022;9781538649015
Image manipulation represents a true “art”, which takes into account the images with a lot of their properties. There are many ways a digital photo can be manipulated, so the forger can use one or more combinations of these in order to make their detection more difficult. On the other hand, only one detection technique is specific to a single image manipulation. For instance, a duplication detection method is based on an existing correlation between the segment of the original image and the copied image. This paper presents a robust Java implementation of an algorithm detecting such a Copy-Move forged pictures.
Machine learning models are vulnerable to adversarial examples which are generated by adding perturbations to clean images. Input transformation defenses were proposed to defend against adversarial examples at test ti...
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ISBN:
(纸本)9781665443326
Machine learning models are vulnerable to adversarial examples which are generated by adding perturbations to clean images. Input transformation defenses were proposed to defend against adversarial examples at test time. However, existing input transformation defenses are demonstrated to be bypassable by advanced attacks. To improve the robustness of input transformation defenses, we identify three essential properties of robust input transformations. Moreover, we propose a key-based input transformation defense which satisfies the three properties. We evaluate the key-based input transformation defense in three experimental settings including black-box, gray-box and white-box based on attackers’ knowledge about the target model and input transformation. We demonstrate that our key-based input transformation is effective against adversarial examples and difficult to be bypassed.
This paper describes an embedded sinusoidal transform codec that is scalable not only in bit-rate, but also in sampling rate. In a representative implementation, the system produces an embedded bit-stream at 3.2 and 6...
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This paper describes an embedded sinusoidal transform codec that is scalable not only in bit-rate, but also in sampling rate. In a representative implementation, the system produces an embedded bit-stream at 3.2 and 6.4 kbit/s for telephone-bandwidth speech, and scales up to 9.6 kbit/s for 16 kHz sampled wideband speech. The 3.2 kbit/s codec is a sinusoidal transform codec with synthetic phases. The 6.4 kbit/s codec adds resolution to the spectral envelope and transmits measured phases of the eight lowest harmonics. The 9.6 kbit/s codec adds information in the 4 to 8 kHz band to provide higher quality wideband speech.
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