Vakil N, Bourgeois K
University of Wisconsin, Milwaukee, USA.
Endoscopy. 1995 Oct;27(8):589-92. doi: 10.1055/s-2007-1005763.
Digital color information is obtained in "bits" or parcels of information for each color (red, green, blue) of a picture. As the number of bits increases, the amount of color information increases, and more colors can be displayed on a suitable monitor. With eight bits of information, 256 colors can be displayed; with 16 bits, several thousand colors can be displayed; and with 24 bits, more than 16 million colors can be displayed. We sought to determine the minimum requirement for diagnostic-quality endoscopy images in a prospective blinded trial.
Twenty-four bit color images were digitally acquired from the processor using a video card and a personal computer. Ten lesions were chosen to represent the gamut of lesions seen in the upper gastrointestinal tract. Images were simultaneously obtained with decreasing color information (16 and eight bits), and these served as controls. Eleven observers were the test subjects. Six endoscopy nurses, who perform color calibrations, and five endoscopists viewed the images. Eight-bit, 16-bit and 24-bit color images were coded and displayed simultaneously on a high-resolution color monitor (Supermac Technology, Sunnyvale, CA) that can display 16.8 million colors.
All images were considered to be of diagnostic quality by the observers, and the area of abnormality was identified and the diagnosis made in all cases. Of 110 viewings of the 24-bit image, on 45 occasions (41%) the viewers could detect no difference between it and the eight-bit and 16-bit images. In 23 (21%), the 24-bit color image was correctly recognized, and on 21 occasions (19%) the 24-bit image was incorrectly identified as eight-bit or 16-bit. Similar data were obtained with viewings of the eight-bit and 16-bit images.
Our results demonstrate that, with current endoscopic technology, 256 colors may be as good as 16 million. Eight-bit color is an acceptable image standard for routine endoscopy.
数字颜色信息是以“位”或图像每种颜色（红、绿、蓝）的信息块形式获取的。随着位数增加，颜色信息量增加，在合适的显示器上就能显示更多颜色。有8位信息时可显示256种颜色；16位时可显示数千种颜色；24位时可显示超过1600万种颜色。我们试图在一项前瞻性双盲试验中确定诊断质量的内镜图像的最低要求。
使用视频卡和个人计算机从处理器中数字采集24位彩色图像。选择10个病变来代表上消化道中见到的病变范围。同时获取颜色信息减少（16位和8位）的图像，并将其作为对照。11名观察者为受试对象。6名进行颜色校准的内镜护士和5名内镜医师查看这些图像。8位、16位和24位彩色图像进行编码后同时显示在一台能显示1680万种颜色的高分辨率彩色显示器（Supermac Technology，加利福尼亚州桑尼维尔）上。
观察者认为所有图像均具有诊断质量，所有病例中均识别出异常区域并做出了诊断。在对24位图像的110次查看中，有45次（41%）观察者无法检测出它与8位和16位图像之间的差异。在23次（21%）中，24位彩色图像被正确识别，在21次（19%）中，24位图像被错误地识别为8位或16位。对8位和16位图像的查看也获得了类似数据。
我们的结果表明，就目前的内镜技术而言，256种颜色可能与1600万种颜色一样好。8位颜色是常规内镜检查可接受的图像标准。
