Lossy data compression generates distortion or error on the reconstructed image and the distortion becomes visible as the compression ratio increases. Even at the same compression ratio, the distortion appears differently depending on the compression method used. Because of the nonlinearity of the human visual system and lossy data compression methods, we have evaluated subjectively the quality of medical images compressed with two different methods, an intraframe and interframe coding algorithms. The evaluated raw data were analyzed statistically to measure interrater reliability and reliability of an individual reader. Also, the analysis of variance was used to identify which compression method is better statistically, and from what compression ratio the quality of a compressed image is evaluated as poorer than that of the original. Nine X-ray CT head images from three patients were used as test cases. Six radiologists participated in reading the 99 images (some were duplicates) compressed at four different compression ratios, original, 5:1, 1 0: 1 , and 1 5 : 1 . The six readers agree more than by chance alone and their agreement was statistically significant, but there were large variations among readers as well as within a reader. The displacement estimated interframe coding algorithm is significantly better in quality than that of the 2-D block DCT at significance level 0.05. Also, 10: 1 compressed images with the interframe coding algorithm do not show any significant differences from the original at level 0.05.
Agriculture is an important source of nitrogen and phosphorous loads to the Baltic Sea. We study how the European Union's (EU) Common Agricultural Policy (CAP), and in particular how its first pillar, containing most of the budget and the decoupled farm payments, affects eutrophication. To aid our study, we use three simulation models, covering the agricultural sector in the EU, a hydrological nutrient flow model and a model of eutrophication in the Baltic Sea. We compute changes in key eutrophication indicators in a business-as-usual baseline and in a hypothetical situation where the first pillar of the CAP, containing the direct payments, greening and accompanying measures, is not present. Comparing the outcomes, we find that in the scenario without the first pillar, production and agricultural land use is lower, while yields and fertiliser use per hectare are higher, causing less nitrogen and phosphorous loads (0.5 to 4% depending on the basin) and less eutrophication in the Baltic Sea as net effect. We therefore conclude that the policies of the first pillar of the CAP contribute to increased eutrophication in the Baltic Sea.
ABS1RACThe image viewing workstation is an all-important link in the PACS (Picture Archiving and Communications System) chain since it represents the interface between the system and the user. For PACS to function, the working environment and transfer of information to the user must be the same or better than the traditional film-based system. The important characteristics of a workstation from a clinical standpoint are acceptable image quality, rapid response time, a friendly user interface, and a well-integrated, highly-reliable, fault-tolerant system which provides the user ample functions to complete his tasks successfully.Since early 1992, the MDIS (Medical Diagnostic Imaging Support ) system's diagnostic and clinical workstations have been installed at Madigan Army Medical Center. Various functionalities and performance characteristics of the MDIS workstations such as image display, response time, database, and ergonomics will be presented. User comments and early experience with the workstations as well as new functionality recommended for the future will be discussed. 336
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