Community Research and Development Information Service - CORDIS

Image compression: Get it right with IQET software

Visual image distortion is the limiting factor of any digital image compression technique. Selection of the compression algorithm, based on user's own visual assessment of the quality of the compressed image is now possible through the IQET software tool.
Image compression: Get it right with IQET software
Image compression is a requirement imposed by existing data transmission technologies. Since the establishment of the Joint Photographic Expert Group (JPEG) compression standard, in 1992, much research has been devoted to image compression. Several special mathematical methods (algorithms) can be used to reduce the size of information (compress) necessary to reproduce a certain visual result (image).

The quality of the compressed image though, is a matter to be judged by the user, which can prove very important, for example, in medical imaging. Each user perceives the quality of a compressed image in a unique way, yet some common ground can be found when visual perception is analyzed into several basic perceptual attributes, such as the perceived sharpness, brightness and contrast. These attributes can, in turn, be determined by physical parameters.

The Image Quality Evaluation Tool (IQET) software provides a common framework for visually optimizing compression algorithms and image quality assessment. Through the graphical interface the user can select a compression algorithm, adjust it, if necessary, and view the resulting compressed image next to the original one. In addition, the so-called Importance-Map, highlights the regions where perceptual errors are more significant.

The software supports the DICOM (Digital Imaging and Communications in Medicine) image format and offers several advanced features, such as multidimensional scaling and perceptual loss-less compression. Moreover, being developed as a MATLAB Toolbox, custom functions, like JPEG200 format support, can be easily added, and the tool can be used both in PCs and UNIX machines.

Useful links :
http://www.jbig.org/JPEG2000.htm
http://www.psychology.nottingham.ac.uk/staff/cr1/dicom.html
Record Number: 80163 / Last updated on: 2005-09-18
Domain: IT, Telecommunications
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