Brettle D S
Department of Medical Physics & Engineering, Leeds Teaching Hospitals NHS Trust, Lincoln Wing, St James's University Hospital, Beckett Street, Leeds LS9 7TF, UK.
Br J Radiol. 2001 Jan;74(877):69-72. doi: 10.1259/bjr.74.877.740069.
Digital imaging is becoming widespread in diagnostic radiology. Most diagnostic digital images do not relate explicitly to the physical processes involved in their generation but are, in essence, a "pseudo" image generated from digital data using pre- and post-processing. Without knowledge of how the image was generated, there is a potential to misinterpret the image data. A new design of digitally generated graphic is presented that is intended to help maintain the frame of reference when viewing digitally processed images. The intention is that the digital frame of reference (DFOR) be included with all digitally processed images and be processed using the same factors as were used on the image. An unprocessed DFOR can then be displayed adjacent to the processed DFOR to re-introduce a frame of reference and to clearly illustrate the effect of any processes that have been applied to the image. This would allow the viewer to perceive any artefacts that may have been introduced into the image by the processing. This is particularly important where the image requires interpretation by the viewer, as in medical diagnosis. This paper presents a grey scale version of the DFOR that is suitable for applications such as medical imaging. The DFOR includes: grey scale from 0 to the maximum bit depth in 0%, 30%, 70% and 100% steps on a 50% background; the full frequency range from 0 to the Nyquist frequency; high, medium and low contrast boundaries; and linear/curvilinear features. The same method could be extended to any other digital image system and could be easily modified to include colour.
数字成像在诊断放射学中越来越普遍。大多数诊断性数字图像与图像生成过程中涉及的物理过程没有直接关联，本质上是使用预处理和后处理从数字数据生成的“伪”图像。如果不知道图像是如何生成的，就有可能错误解读图像数据。本文提出了一种新设计的数字生成图形，旨在帮助在查看数字处理图像时保持参考框架。目的是使数字参考框架（DFOR）与所有数字处理图像一起包含，并使用与图像相同的因素进行处理。然后，可以将未处理的DFOR显示在已处理的DFOR旁边，以重新引入参考框架，并清楚地说明应用于图像的任何处理的效果。这将使观察者能够察觉到处理过程中可能引入到图像中的任何伪影。在观察者需要对图像进行解读的情况下，如医学诊断，这一点尤为重要。本文介绍了一种适用于医学成像等应用的DFOR灰度版本。DFOR包括：在50%背景上，灰度从0到最大比特深度，以0%、30%、70%和100%步长变化；从0到奈奎斯特频率的全频率范围；高、中、低对比度边界；以及线性/曲线特征。同样的方法可以扩展到任何其他数字图像系统，并且可以很容易地修改为包含颜色。
