Borchers J, Klews P M
Philips Medizin Systeme, Hamburg.
Ultraschall Med. 1993 Oct;14(5):214-9. doi: 10.1055/s-2007-1005250.
With the help of workstations and PCs, on-site image processing has become possible. If the images are not available in digital form the video signal has to be A/D converted. In the case of colour images the colour channels R (red), G (green) and B (blue) have to be digitized separately. "Truecolour" imaging calls for an 8 bit resolution per channel, leading to 24 bits per pixel. Out of a pool of 2(24) possible values only the relevant 128 gray values and 64 shades of red and blue respectively needed for a colour-coded ultrasound image have to be isolated. Digital images can be changed and evaluated with the help of readily available image evaluation programmes. It is mandatory that during image manipulation the gray scale and colour pixels and LUTs (Look-Up-Table) must be worked on separately. Using relatively simple LUT manipulations astonishing image improvements are possible. Application of simple mathematical operations can lead to completely new clinical results. For example, by subtracting two consecutive colour flow images in time and special LUT operations, local acceleration of blood flow can be visualized (Colour Acceleration Imaging).
借助工作站和个人电脑，现场图像处理已成为可能。如果图像不是数字形式，就必须对视频信号进行模数转换。对于彩色图像，颜色通道R（红色）、G（绿色）和B（蓝色）必须分别数字化。“真彩色”成像要求每个通道有8位分辨率，即每个像素24位。在总共2(24)种可能的值中，只需分离出彩色编码超声图像所需的相关128个灰度值以及分别64种红色和蓝色色调。借助现有的图像评估程序可以对数字图像进行更改和评估。在图像处理过程中，必须分别处理灰度像素、彩色像素和查找表（LUT）。通过相对简单的查找表操作，有可能实现惊人的图像改善。应用简单的数学运算可以带来全新的临床结果。例如，通过及时减去两个连续的彩色血流图像并进行特殊的查找表操作，可以可视化局部血流加速（彩色加速度成像）。
