Search results for " JPEG"
showing 4 items of 4 documents
The effect of wavelet and discrete cosine transform compression of digital radiographs on the detection of subtle proximal caries. ROC analysis.
2007
The study compared diagnostic performances of 2 different image compression methods: JPEG (discrete cosine transform; Joint Photographic Experts Group compression standard) versus JPEG2000 (discrete wavelet transform), both at a compression ratio of 12:1, from the original uncompressed TIFF radiograph with respect to the detection of non-cavitated carious lesions. Therefore, 100 approximal surfaces of 50 tooth pairs were evaluated on the radiographs by 10 experienced observers using a 5-point confidence scale. Observations were carried out on a standardized viewing monitor under subdued light conditions. The proportion of diseased surfaces was balanced to approximately 50% to avoid bias. Tr…
Dynamic QoS management for multimedia real-time transmission in industrial environments
2007
The use of multimedia within industrial applications has become commonplace, targetting improved process monitoring and machine vision. In both cases, the multimedia information is commonly distributed and subject to time constraints that must be met across networks while avoiding untolerable interference over typical control flows. This can be achieved with Constant Bit-Rate (CBR) channels, typically supported by real-time protocols. However, the compressors used to reduce the amount of information to transfer generate Variable Bit-Rate (VBR) patterns. Adapting a VBR source to a CBR channel requires specific care in order to avoid wasting channel bandwidth or dropping video frames. This pa…
Statistical Modeling of Huffman Tables Coding
2005
An innovative algorithm for automatic generation of Huffman coding tables for semantic classes of digital images is presented. Collecting statistics over a large dataset of corresponding images, we generated Huffman tables for three images classes: landscape, portrait and document. Comparisons between the new tables and the JPEG standard coding tables, using also different quality settings, have shown the effectiveness of the proposed strategy in terms of final bit size (e.g. compression ratio).
A new algorithm for bit rate allocation in JPEG2000 tile encoding
2004
A new algorithm for allocating a given bit rate to different image tiles in the JPEG2000 encoding system is proposed. The algorithm outperforms other approaches commonly used in implementations. The new algorithm is suitable when information content is not equally distributed across the image. It is based on the computation of an index of the information content of each tile. To implement the proposed approach, we modified JasPer, a free software-based JPEG2000 coder implementation (Adams, M.D. and Kossentini, F., Proc. IEEE Int. Conf. on Image Process., vol.2, p.53-6, 2000). The experimentation was carried out on a subset of the JPEG2000 test images. Experimental results are reported, show…