In this paper, we address the problem of scrambling regions of interest in a video sequence. We target applications such as video surveillance preserving privacy, anonymous video communications, or TV news safeguarding the anonymity of a source. We propose an efficient solution based on transform-domain scrambling. More specifically, the sign of selected transform coefficients is flipped during...

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...

∗ Corresponding author. Fax: +30 61 997456 Email addresses: [email protected] (A.N. Skodras), [email protected] (C.A. Christopoulos), [email protected] (T. Ebrahimi). Abstract: With the increasing use of multimedia technologies, image compression requires higher performance as well as new features. To address this need in the specific area of still image encoding, a ne...

In this paper, we review the various tools in JPEG-2000 that allow the users to take advantages of the various properties of the human visual system such as spatial frequency sensitivity and the visual masking effect. We show that the visual tool sets in JPEG-2000 are much richer than what was available in JPEG, where only locally invariant frequency weighting can be exploited

Scalable encoded information, as in the JPEG 2000 standard, results in files which can be truncated at an arbitrary point and decoded. This work introduces a tractable, yet flexible model appropriate for resource management involving scalably encoded information. At its core is a function yielding a measure of “quality” of the decoded information as a function of the number of bits chosen for d...

With the increasing use of multimedia technologies, image compression requires higher performance as well as new functionality. To address this need in the specific area of still image encoding, a new standard is currently being designed: JPEG2000. We will see in this paper what the exact goals are of this future standard, which applications it addresses and the current standardisation process....

When it comes to image coding, JPEG is the first thing that comes to mind. JPEG is the most widely used compression Standard for true color continuous-tone images. It was created by the Joint Photographic Experts Group (http://www.jpeg.org/) around 10 years ago, and although it delivers good quality at lowand medium-compression ratios, it lacks flexibility of use and its quality at high compres...

In this paper, a method for measuring the perceptual image quality of JPEG-2000 coded images has been proposed. The image quality is characterized by the average edgespread in the image, or more specifically the average extent of the slope’s spread of an edge in the opposing gradients’ directions. The proposed method is, in effect, a way of measuring the amount of blurring in the image. The eff...

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