摘要:
An x-ray imaging system (40) includes a source of x-rays (42), a video camera (52) which produces an image signal formed by x-ray attenuation values, an image signal processor (72) and a video monitor (74) for displaying the x-ray image. The system also has an automatic image control (56) that includes a peak detector (60), an average brightness detector (58) and a transfer function generator (62) for the image processor. The peak detector (60) receives the image signal and produces a video gain control signal for controlling the video camera in response to a comparison of a peak level of the image signal to a peak reference level. The average brightness detector (58) employs the image signal to produce a feedback signal (66) which controls by the source of x-rays. The transfer function generator (62) produces a histogram of intensity levels in the image signal which histogram forms a look-up table (76) that is used by the image processor to transform the image signal into the adjusted image signal for display.