Key Parameters Of Medical Imaging Display--Grayscale
The medical digital subtraction angiography system and mobile C arm X-ray machine are equipped with at least two displays. One is for real-time monitoring in the operation room, another is in the control room. And grayscale performance is one of the indexes for medical display.
Grayscale refers to the level that the display can display between the brightest value and the darkest value. Grayscale is an important parameter for truly displaying patient lesions in medical images, only with more grayscale levels, a higher reading quality can be guaranteed. The ordinary monitor has 8bit-256 grayscale, used to display color images, with no gray level requirements. The medical display has 10bit-1024 grayscale, which is used to display X-ray grayscale images, and is relevant for diagnosis.
The response of the human eyes to the gray scale is not linear, because our eyes are less sensitive to the dark parts than to the bright parts. Provides there is a standard display function for displaying grayscale images in Chapter 14 of DICOM3.0. By using this standard display function to display images on display systems of different brightness, a certain degree of similarity can be provided. After the grayscale is transformed by this function, the response of the human eyes is approximately linear.
Therefore, a good medical monitor must have the function of adjusting the gray-scale display curve to conform to the gray-scale display function specified in Chapter 14 of DICOM3.0.
In radiological diagnosis, this grayscale difference may be of great help in the diagnosis of early lesions. The number of grayscales that the monitor displays in black and white images are related to the graphics card. Ordinary graphics cards are more concerned with color display parameters. However, the windows system is an 8bit output display, which reflects the grayscale of black and white images, or 256 grayscales. Because windows have 20 exclusive colors on the palette, there are actually only 236 grayscales in the image, which is why the grayscale discontinuity is often encountered by ordinary graphics cards. To achieve the perfect reproduction of black and white images with continuous grayscale, a professional graphics card with a grayscale output of more than 10bit should be selected.
