Giger M L, Doi K
J Opt Soc Am A. 1987 May;4(5):966-75. doi: 10.1364/josaa.4.000966.
The effect of pixel size and other physical parameters on the detectability of simple signals in digital radiography was investigated using a signal-to-noise ratio (SNR) that is based on statistical decision theory and takes into account the characteristics of the human observer. The calculation of the SNR includes two-dimensional displayed digital signal spectra and noise Wiener spectra as well as the visual-response function and internal noise of the human observer. Threshold contrasts derived from calculated SNR's agreed well with results of an 18-alternative forced-choice observer study. Since a digital imaging system is not shift invariant, the threshold contrasts were determined for a range of alignments of the object relative to the sampling coordinates. The results indicate that a 0.2-mm pixel size may be adequate for visual detection of necessary detail in most digital radiographic examinations.
利用基于统计决策理论并考虑人类观察者特征的信噪比（SNR），研究了像素大小和其他物理参数对数字射线照相中简单信号可检测性的影响。SNR的计算包括二维显示的数字信号谱和噪声维纳谱，以及人类观察者的视觉响应函数和内部噪声。从计算出的SNR得出的阈值对比度与18选1强制选择观察者研究的结果非常吻合。由于数字成像系统不是平移不变的，因此针对物体相对于采样坐标的一系列对齐方式确定了阈值对比度。结果表明，在大多数数字射线照相检查中，0.2毫米的像素大小可能足以用于视觉检测必要的细节。
