Shrout M K, Potter B J, Yurgalavage M H, Hildebolt C F, Vannier M W
Medical College of Georgia, School of Dentistry, Augusta.
Oral Surg Oral Med Oral Pathol. 1993 Oct;76(4):510-8. doi: 10.1016/0030-4220(93)90021-u.
Typical 35-mm slide scanners use a photodiode array and software that allows for digital and analog controls that are manually adjustable. The digital controls provide brightness and contrast adjustments, whereas corresponding analog controls adjust the exposure time and black level that determines the clamping level of the charge-coupled device for the maximum black in the image. The objective of this study was to determine the effects of these controls on the radiometric data of intraoral dental radiograph images, to establish recommended settings, and to set specific standard guidelines for the digitization process. Three approaches were used. The results of this study demonstrate that brightness and contrast control alterations on the digitizer produces different optical densities and modulation transfer function values. The impact of these results is unresolved yet must be considered in analysis on quantitative radiometric studies.
典型的35毫米幻灯片扫描仪使用光电二极管阵列和软件，该软件允许进行手动可调的数字和模拟控制。数字控制提供亮度和对比度调整，而相应的模拟控制则调整曝光时间和黑电平，黑电平决定了电荷耦合器件在图像中最大黑色时的钳位电平。本研究的目的是确定这些控制对口腔内牙科X线图像辐射数据的影响，建立推荐设置，并为数字化过程设定具体的标准指南。采用了三种方法。本研究结果表明，数字化仪上亮度和对比度控制的改变会产生不同的光学密度和调制传递函数值。这些结果的影响尚未得到解决，但在定量辐射研究分析中必须予以考虑。
