LOSSILY COMPRESSED MEDICAL MODALITIES: OBJECTIVE AND SUBJECTIVE QUALITY MEASURES IN RELEVANT TO THE STATISTICAL AND FREQUENCY EVALUATIONS
OH TICK HUI · Journal of Mechanics in Medicine and Biology · 2004
Compressed image will always reduce the image fidelity. This is especially so if the image is compressed at lower bit rates, which most of the time cannot be tolerated. In medical field, this is even more significant. But compression is necessary due to the limited transmission bandwidth and storage capacity. In this paper, the lossy compression performance of the new JPEG2000 and the more conventional JPEG is being studied. The common objective measure, peak signal-to-noise ratio (PSNR) is definitely not adequate as a perceptual quality measurement. Therefore, subjective measures such as picture quality scale (PQS) and mean opinion score (MOS) are included, plus the statistical and frequency measures for the image characteristics evaluation. Four types of medical modalities are used — X-Ray, Magnetic Resonance Imaging (MRI), Ultrasound, and Computed Tomography (CT). From these various measurements, the general acceptance compression bit rate for each of the medical modality is determined.