Region Of Interest (ROI) coding is one of the innovative functionalities supported by JPEG 2000, the new ISO/ITU-T still image coding standard developed by the Joint Photographic Experts Group (JPEG). It enables a non-uniform distribution of the image quality between a selected region (the ROI) and the rest of the image (background). This feature is obtained by scaling background coefficients i...

This paper presents an efficient authentication method for JPEG images based on Genetic Algorithms (GA). The current authentication methods for JPEG images require the receivers to know the quantization table beforehand in order to authenticate the images. Moreover, the quantization tables used in the JPEG compression are different for different quality factors, thus increasing the burden on th...

lossless image compression, standards LOCO-I (LOw COmplexity LOssless COmpression for Images) is the algorithm at the core of the new ISO/ITU standard for lossless and near-lossless compression of continuous-tone images, JPEG-LS. The algorithm, presented at DCC'96, was conceived as a “low complexity projection” of the universal context modeling paradigm, matching its modeling unit to a simple c...

Steganography and steganalysis of digital images is a catand-mouse game. In recent work, Fridrich, Goljan and Du introduced a method that is surprisingly accurate at determining if bitmap images that originated as JPEG les have b en altered (and even specifying where and how they were altered), even if only a single bit has been changed. However, steganographic embeddings that encode embedded d...

The need for high-performance image compression is becoming greater and greater as digital imagery finds its way into many areas of everyday life. JPEG2000 is the state-of-the-art compression standard emerges from the Joint Photographic Experts Group (JPEG) working under the auspices of the International Standards Organization. The new standard out performs the older JPEG standard by approximat...

JPEG compression based on the discrete cosine transform (DCT) is a key building block in low-power multimedia applications. Approximate computation techniques are used to exploit the error tolerance of JPEG. An image-dependent framework is proposed in this work to design optimized approximate hardware with variable approximate bit-widths for a userspecified error budget. The proposed method can...

Better methods and tools are needed in the fight against child pornography. This thesis presents amethod for file type categorisation of unknown data fragments, a method for reassembly of JPEGfragments, and the requirements put on an artificial JPEG header for viewing reassembled images.To enable empirical evaluation of the methods a number of tools based on the methods have been<lb...

In this paper, we propose a semi-fragile watermarking technique that accepts JPEG lossy compression on the watermarked image to a pre-determined quality factor, and rejects malicious attacks. The authenticator can identify the positions of corrupted blocks, and recover them with approximation of the original ones. In addition to JPEG compression, adjustments of the brightness of the image withi...