1. Angiographic process utilizing contrast mediums for the roentgenographic representation of living organ vessels, especially human, wherein a reference radiograph is made of a vascular region to be visualized, a contrast medium is infused into said vascular region, a photograph of the same region is produced after a given time interval, for example 0.5 seconds and a visual image is produced by photographic substraction of the two pictures, wherein the process further comprises the steps of reducing the quantity of the contrast medium and the x-ray dose used to produce the pictures by photographically equivalent factors to such an extent that the desired information lies in a density range (blackening range) unsuited to direct observation, and extracting and transposing in the process of photographic subtraction, the density range containing the information into a visual density range suitable for direct observation of the image.