Castella Cyril, Abbey Craig K, Eckstein Miguel P, Verdun Francis R, Kinkel Karen, Bochud François O
University Institute for Radiation Physics, Centre Hospitalier Universitaire Vaudois (CHUV), University of Lausanne, Grand-Pré 1, CH-1007 Lausanne, Switzerland.
J Opt Soc Am A Opt Image Sci Vis. 2007 Dec;24(12):B1-12. doi: 10.1364/josaa.24.0000b1.
We estimated human observer linear templates underlying the detection of a realistic, spherical mass signal with mammographic backgrounds. Five trained naïve observers participated in two-alternative forced-choice (2-AFC) detection experiments with the signal superimposed on synthetic, clustered lumpy backgrounds (CLBs) in one condition and on nonstationary real mammographic backgrounds in another. Human observer linear templates were estimated using a genetic algorithm. A variety of common model observer templates were computed, and their shapes and associated performances were compared with those of the human observer. The estimated linear templates are not significantly different for stationary CLBs and real mammographic backgrounds. The estimated performance of the linear template compared with that of the human observers is within 5% in terms of percent correct (Pc) for the 2-AFC task. Channelized Hotelling models can fit human performance, but the templates differ considerably from the human linear template. Due to different local statistics, detection efficiency is significantly higher on nonstationary real backgrounds than on globally stationary synthetic CLBs. This finding emphasizes that nonstationary backgrounds need to be described by their local statistics.
我们估计了在具有乳腺X线摄影背景的情况下检测逼真的球形肿块信号时人类观察者的线性模板。五名经过训练的新手观察者参与了二择一强制选择（2-AFC）检测实验，一种情况下信号叠加在合成的簇状块状背景（CLB）上，另一种情况下叠加在非平稳的真实乳腺X线摄影背景上。使用遗传算法估计人类观察者的线性模板。计算了各种常见的模型观察者模板，并将它们的形状和相关性能与人类观察者的进行了比较。对于平稳的CLB和真实乳腺X线摄影背景，估计的线性模板没有显著差异。在2-AFC任务中，线性模板的估计性能与人类观察者相比，正确率（Pc）在5%以内。通道化霍特林模型可以拟合人类的性能，但模板与人类线性模板有很大差异。由于局部统计不同，非平稳真实背景上的检测效率显著高于全局平稳的合成CLB。这一发现强调，非平稳背景需要用其局部统计来描述。
