Narrow Results

With the ambient use of digital images and the increasing concern on their integrity and originality, consumers are facing an emergent need of authenticating degraded images despite lossy compression and packet loss. In this paper, we propose a scheme to meet this need by incorporating watermarking solution into traditional cryptographic signature scheme to make the digital signatures robust to these image degradations. Due to the unpredictable degradations, the pre-processing and block shuffling techniques are applied onto the image at the signing end to stabilize the feature extracted at the verification end. The proposed approach is compatible with traditional cryptographic signature scheme except that the original image needs to be watermarked in order to guarantee the robustness of its derived digital signature. We demonstrate the effectiveness of this proposed scheme through practical experimental results.

A novel JPEG2000-based algorithm, termed quality pre-specifiable layered JPEG2000 (QPSL-JPEG2000), for realizing a layered image transmission (LIT) system is presented in this paper. In the QPSL-JPEG2000 algorithm, the resolution and rate associated with each layer of the LIT system can be pre-specified. It encodes an image one layer at a time using the modified JPEG2000 technique. The encoding process at each layer only covers the subbands having resolution level lower than the designated resolution at that layer subject to the pre-specified incremental rate budget. The encoding results at the previous layers will be used in the current layer to accelerate the encoding process. Numerical results show that the QPSL-JPEG2000 algorithm outperforms its counterparts for constructing the rate and resolution pre-specified LIT systems.

Despite their frequent use in our daily life, the expansion and reduction of images are among the least studied research areas in the literature. That is why the present research paper undertakes the study of the different techniques used for reducing and enlarging images, whose combination will be a new protocol (REPro) for the transmission of medical images. The proposed approach consists in reducing the image when sent and enlarging it when received, which allows for consumption saving of the bandwidth allocated to the diagnostics service. To do so, the performance of our new protocol was tested for the transfer of scars images (color images) and ultrasound images (grayscale images) in terms of the resemblance between the original image, on one hand, and the reduced and then enlarged one, on the other hand.

In this chapter, we describe several fixed length coding schemes based on trellis coded quantization (TCQ) that have been developed for image transmission over noisy channels such as wireless links. In general, wireless channels are time-varying, bandwidth constrained, and error pruned. Therefore, it is desired that the images are not only appropriately coded to achieve bandwidth compression, but also coded in such a way that the coded bitstream is resilient to channel errors and robust to time-varying channel distortion and fading. The proposed schemes consist of the basic algorithm of uniform threshold TCQ (UTTCQ) and two enhanced schemes with increased computational complexity. The enhanced schemes include nonuniform threshold TCQ and UTTCQ with block classification. We demonstrate that, in the absence of channel coding, the proposed fixed length coding schemes can be designed to achieve efficient compression, error resilience, and robustness. In particular, the fixed length coding schemes will not suffer from the loss of synchronization that often causes catastrophic error effects when more efficient variable length source coding is adopted. We also present a scheme of layered transmission with unequal error protection channel coding to further improve the performance of image transmission over noisy channels.

In recent years, we have observed an explosion in the growth of the internet. One major advantage of the world wide web is that it provides a platform for people to easily share documents, images, and other forms of contents. In this paper we focus on imaging applications for the internet. In particular, we will describe technologies that are designed for internet imaging applications. These include systems and algorithms for the efficient transmission and sharing of images over the network. Important image processing problems such as multiresolution imaging, remote printing, image security, watermarking, and secure printing are considered.

The original image transmission protocol based on WMSNs cannot meet the requirements for stable, reliable and real-time transmission because of the restricted transmission bandwidth and unstable communication link. To obtain abundant image information based on WMSNs, research on image transmission is necessary. In order to improve performance in terms of transmission reliability, transmission delay and node mortality, a multi-path crossed node rotation (MPCNR) protocol based on wireless sensor networks was proposed in this paper. The MPCNR protocol chooses multiple paths in parallel transmission expansion of bandwidth, puts forward the nodes with the same communication ability in each path, forming a cluster, and selects the most powerful node in the same cluster as a relay routing nodes to improves transmission stability and avoid large scale node death. A network simulation model by MATLAB was built to analyse the transmission reliability, the end-to-end delay and the number of surviving nodes. The simulation results show that, compared with the traditional image transmission protocol, the MPCNR protocol can improve performance in transmission reliability, transmission delay and node mortality. These findings are significant for image transmission based on wireless sensor networks.