Abstract: X-ray diagnostic apparatus is disclosed which includes a video camera; at least one image memory (12); one subtraction stage (13) for producing subtraction images by forming the difference from a stored video signal and a video signal chronologically following the stored video signal; an evaluation circuit (14 to 21) for evaluating the time of the difference signal; and a color video monitor (7). The evaluation circuit (14 to 21) contains a time stage (15) and a color converter (14). The color converter (14) is directly coupled to the subtraction stage (13) and converts the subtraction image into a black and white (monochrome) intensity image whose image color is controlled by the time stage (15) in dependence upon the chronological occurrence of the subtraction image. The color converter (14) has one output for each of the primary colors (red, green, blue). One memory (16 to 18) is coupled to each of these outputs for the storing of the output signals of the color converter (14) by summation.

Abstract: A method and apparatus for use in a medical x-ray imaging system of the type including an x-ray source, an image intensifier tube for providing a momentary x-ray image of a patient exposed to x-rays and a video camera having video processing circuits for providing signals representative of a video image of the x-ray image on the intensifier tube to a video monitor provides a flickerless image presentation on the video monitor when the x-ray exposure repetition rate is different from the field scan rate of the video camera. The apparatus enables this result by sensing initiation of a first x-ray exposure and setting the amplification of the video processing circuits to a first value for obtaining a suitable presentation of the image. The apparatus then scans the image on the video camera to provide a first field of image presentation to the video monitor with the amplification set at the first value.