نتایج جستجو برای: تصویر jpeg

تعداد نتایج: 21751  

2007
Guorong Xuan Yun Q. Shi Zhicheng Ni Peiqi Chai Xia Cui Xuefeng Tong

This paper proposes a lossless data hiding technique for JPEG images based on histogram pairs. It embeds data into the JPEG quantized 8x8 block DCT coefficients and can achieve good performance in terms of PSNR versus payload through manipulating histogram pairs with optimum threshold and optimum region of the JPEG DCT coefficients. It can obtain higher payload than the prior arts. In addition,...

2005
Konrad Froitzheim Heiner Wolf

JPEG picture compression and related algorithms are not only used in still picture compression, but also to a growing degree for moving picture compression in telecommunication applications. Real-time JPEG compression and decompression are crucial in these scenarios. We present a method to significantly improve the performance of software based JPEG decompression. Key to these performance gains...

2009
Lakshmanan Nataraj Anindya Sarkar B. S. Manjunath

In this paper, we propose robust methods to detect image resizing. A common problem affecting most resizing detection algorithms is that they are susceptible to JPEG compression attacks. The reason is that JPEG compression introduces its own periodicity, as it works on 8×8 blocks. In our proposed approach, we add a suitable amount of Gaussian noise to a resized and JPEG compressed image so that...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شیراز - دانشکده مهندسی برق 1390

اگرچه روشهای زیادی تا به حال برای فشرده سازی تصاویر پیشنهاد شده است که یکی از پرکاربردترین آنها jpeg(joint photographic experts group) است، ولی به استفاده از روش های حذف اطلاعات به صورت هوشمندانه متناسب با مدلهای دیداری و در جهت بازسازی کاراتر کمتر توجه شده است. با معرفی وپیشرفت تکنیک هایی مانند ترمیم، که امکان بازسازی نواحی مخدوش تصویر را به ما میدهند، این ایده مطرح شد که در فرستنده بخشهایی از...

Journal: :J. Electronic Imaging 2008
Yu-Jie Chang Sian-Jheng Lin Ja-Chen Lin

This work presents an authentication and cross-recovery scheme to protect a group of n JPEG images. Given n images, the images are scaled down and then encoded using JPEG to create n recovery data. Based on a pre-determined threshold t, 2 ≤ t < n, the n recovery data are shared to create n shadows. Next, n authentication data are generated to identify malicious attacks on the system. Additional...

2003
José Salvado Bruno Roque

This paper addresses the most relevant aspects of lossy image coding techniques, and presents an evaluation study on this subject, using several transforms and different methods in the transform domain. We developed different transform based image coders/decoders (codecs) using different transforms, such as the discrete cosine transform, the discrete wavelet transform and the S transform. Besid...

Journal: :Sig. Proc.: Image Comm. 2002
Wenjun Zeng Scott J. Daly Shawmin Lei

The human visual system plays a key role in the final perceived quality of the compressed images. It is therefore desirable to allow system designers and users to take advantage of the current knowledge of visual perception and models in a compression system. In this paper, we review the various tools in JPEG-2000 that allow its users to exploit many properties of the human visual system such a...

2000
D. Santa-Cruz T. Ebrahimi J. Askelöf M. Larsson C. A. Christopoulos

JPEG 2000, the new ISO/ITU-T standard for still image coding, is about to be finished. Other new standards have been recently introduced, namely JPEG-LS and MPEG-4 VTC. This paper compares the set of features offered by JPEG 2000, and how well they are fulfilled, versus JPEG-LS and MPEG-4 VTC, as well as the older but widely used JPEG and more recent PNG. The study concentrates on compression e...

2003
V. G. Ruiz

The MPEG-2 standard is the most used codec for video compression. This paper investigates the consequence of replacing the JPEG core system of the MPEG-2 video codec by a progressive image codec, specifically JPEG 2000, so creating a video codec (VC) that can match any desired bit rate. The quality of compressed video sequences between MPEG-2 and VC is compared. Results show that our codec impr...

Journal: :D-Lib Magazine 2009

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