A method for correcting the image data representing the blood flow for the evaluation and quantitative representation of the blood flow in a tissue or vascular region is based on the signal of a contrast agent injected into the blood. Several individual images of the signal emitted by the tissue or vascular region are recorded and stored at successive points in time. At least two individual images are correlated and a shift vector is generated based on the correlation. Thereafter, the image data of the individual images are shifted in relation to each other according to the shift vector.