1. An X-ray diagnostic installation comprising: an X-ray source which emits X-rays; an X-ray detector disposed to detect X-rays from said X-ray source and for generating an electrical signal sequence dependent on the detected X-rays; an imaging system supplied with said electrical signal sequence for processing said electrical signal sequence to generate an image signal; a playback device supplied with said image signal for generating a visual representation therefrom, said visual representation being subject to comet artifacts; and said imaging system including a correction device for correcting said comet artifacts, said correction device including an evaluation unit which analyzes said comet artifacts to produce an evaluation result, a reference value estimator supplied with said evaluation result and with said electrical signal sequence for determining a reference value at locations in said representation disturbed by said comet artifacts, a detail estimator supplied with said analysis result and said electrical signal sequence for determining a detail signal at said locations in said representation disturbed by said comet artifacts, and a combining unit supplied with said reference value and said detail signal which combines said reference value and said detail signal to generate a correction signal applied to said image signal.