T03镜头图像测试卡Depth Of Modulation 0.5/5 MHz。The T03 is designed for evaluating the uniformity of the modulation depth of TV cameras. Between the line raster rows two white bars of different lengths are arranged on a black background (upper part) resp. two black bars of different lengths are arranged on a white background (bottom part).
用空间频率响应SFR （Spatial Frequency Response）来衡量，也称为调制传递函数MTF （Modulation Transfer Function）。MTF是指某一特定空间频率（以周期或线对/单位距离表示）的对比度。用“50％MTF”来表示锐度的方法大大优于旧的表示方法，50 ％MTF表明细节从这个频率开始消失。在打印或显示系统中衡量锐度的指标是主观质量因素SQF（Subjective Quality Factor），源于人类视觉系统的MTF和对比敏感度CSF(Contrast SensitivityFunction)。
