Computer-implemented method of processing magnetic resonance lung images of a subject under investigation, comprising the steps of - providing a series of the MR lung images collected during multiple ventilation periods, - registering the MR lung images for creating a series of registered MR lung images, - determining a ventilation frequency from the registered MR lung images, - creating a series of ventilation images by applying a ventilation frequency based low-pass frequency filter on the registered MR lung images, and - creating a quantitative ventilation map of the lung, which is calculated from the ventilation images, characterized in that - the step of determining the ventilation frequency includes a frequency analysis of a time series of a quantitative lung dimension parameter which is characteristic for the dimension of the lung at the time of collecting the corresponding MR lung image, and - the step of creating the quantitative ventilation map includes - selecting a first group of ventilation images, which consists of expiration ventilation images collected at regular expiration phases of the multiple ventilation periods, wherein the first group of ventilation images is selected by retrospective gating of the time series of the quantitative lung dimension parameter, - selecting a second group of ventilation images, which consists of inspiration ventilation images collected at regular inspiration phases of the multiple ventilation periods, wherein the second group of ventilation images is selected by retrospective gating of the time series of the quantitative lung dimension parameter, wherein the retrospective gating comprises an assignment of values of the quantitative lung dimension parameter to predetermined intervals of the quantitative lung dimension parameter and a determination of regular ventilation events by counting the number of assigned values in each interval, wherein the intervals with maximum numbers of assigned values and the ventilation images associated with the values assigned to those intervals are provided as regular ventilation phases, and - calculating the quantitative ventilation map from the first and second groups of ventilation images, wherein the quantitative ventilation map is adjusted with reference to the tidal volume of the lung. - providing a series of the MR lung images collected during multiple ventilation periods, - registering the MR lung images for creating a series of registered MR lung images, - determining a ventilation frequency from the registered MR lung images, - creating a series of ventilation images by applying a ventilation frequency based low-pass frequency filter on the registered MR lung images, and - creating a quantitative ventilation map of the lung, which is calculated from the ventilation images, characterized in that - the step of determining the ventilation frequency includes a frequency analysis of a time series of a quantitative lung dimension parameter which is characteristic for the dimension of the lung at the time of collecting the corresponding MR lung image, and - the step of creating the quantitative ventilation map includes - selecting a first group of ventilation images, which consists of expiration ventilation images collected at regular expiration phases of the multiple ventilation periods, wherein the first group of ventilation images is selected by retrospective gating of the time series of the quantitative lung dimension parameter, - selecting a second group of ventilation images, which consists of inspiration ventilation images collected at regular inspiration phases of the multiple ventilation periods, wherein the second group of ventilation images is selected by retrospective gating of the time series of the quantitative lung dimension parameter, wherein the retrospective gating comprises an assignment of values of the quantitative lung dimension parameter to predetermined intervals of the quantitative lung dimension parameter and a determination of regular ventilation events by counting the number of assigned values in each interval, wherein the intervals with maximum numbers of assigned values and the ventilation images associated with the values assigned to those intervals are provided as regular ventilation phases, and - calculating the quantitative ventilation map from the first and second groups of ventilation images, wherein the quantitative ventilation map is adjusted with reference to the tidal volume of the lung.