NON ROC MEASURES FOR EVALUATING IMAGE COMPRESSION

描述：当前使用ROC风格观察员性能的趋势 评估图像压缩方案的研究是低效的， 限制了我们认证用于射线照相的特定技术的能力 图像. 该项目的目标是开发更高效的自动化 评估图像压缩效果的技术，但 独立于任何特定压缩方法。 两种方法将是 追求。 首先，我们将制定保真度措施，可适用于 图像的原始版本和压缩版本之间的差异。 这些将不仅基于差异图像的幅度， 也在这个形象的结构，并应克服的局限性， 更简单的测量，如均方误差。 我们将设计 这些措施的合理假设是什么因素是重要的 而不是直接基于心理视觉理论。 虽然这些措施 不能期望与观察者的表现高度相关，因为 小级别的图像退化，他们应该是有用的， 诊断性能的预期损失。 其次，将设计一个数字体模，可用于评估 任何压缩技术和压缩比。 这个幻影 通过上述措施进行评估。 使用体模会更有效 因为它可以对每种压缩技术进行一次， 评估每个图像的测量的必要性。 最后，我们将尝试应用这两种方法来分析的数据库， 目前正在使用的图像在我们的观察者性能研究的图像 压缩和图像分辨率。 作为其中的一部分， 物理措施正在开发ROC结果从这些研究。

DESCRIPTION: The current trend of using ROC style observer performance studies to evaluate image compression schemes is inefficient and has greatly limited our ability to certify particular techniques for use on radiographic images. The goal of this project is to develop more efficient automated techniques for evaluating the efficacy of image compression, but which are independent of any particular compression method. Two approaches will be pursued. First, we will develop fidelity measures which can be applied to the difference between an original and compressed version of an image. These will be based on not only the magnitude of the difference image but also on the structure in this image, and should overcome the limitations of simpler measures such as mean square error. We will base the design of these measures on plausible hypotheses about what factors are important rather than on psycho-visual theory directly. Although these measures cannot be expected to be highly correlated to observer performance, for small levels of image degradation they should be useful for placing limits on the expected loss of diagnostic performance. Secondly, a digital phantom will be designed which can be used to evaluate any compression technique and compression ratio. This phantom would be evaluated with the above measures. Use of a phantom would be more efficient since it could be done once for each compression technique and would avoid the necessity of evaluating a measure for each image. Finally, we will attempt to apply both methods to analyze the databases of images currently being used in our observer performance studies on image compression and on image resolution. As part of this we will correlate the physical measures being developed to ROC results from these studies.