Device for obtaining a vital sign of a subject, the device comprising: - an interface for receiving a set of image frames of a subject; - a motion analysis unit for analysing at least one measurement area within the image frames of said set of image frames and for characterizing motion of the subject within said set of image frames, said motion analysis unit comprising - a motion estimation unit for locally and/or globally estimating motion of the subject based on spatial similarities of pixels or pixel groups over consecutive image frames, - a spatial characteristic extraction unit for globally extracting motion of the subject based on a displacement of a spatial characteristic of a group of pixels exhibiting the same or similar properties, and - a motion characterization unit for determining the type of motion of the subject within said set of image frames as either in-plane or out-of-plane motion by calculating a similarity measure of the similarity of the outputs of said motion estimation unit and said spatial characteristic extraction unit; - a signal extraction unit for extracting photoplethysmographic, PPG, signals from said set of image frames and configured to use said characterization of motion of the subject within said set of image frames to extract said PPG signals only from image frames showing no or substantially no out-of-plane motion or for replacing parts of said PPG signals extracted from image frames showing out-of-plane motion by interpolated signal parts. or to reduce the size of the at least one measurement area, from which PPG signals are extracted, in case of out-of-plane motion of the subject, in particular to extract PPG signals only from a central area of the at least one measurement area; and - a vital signs determination unit for determining vital sign information from said extracted PPG signals. - an interface for receiving a set of image frames of a subject; - a motion analysis unit for analysing at least one measurement area within the image frames of said set of image frames and for characterizing motion of the subject within said set of image frames, said motion analysis unit comprising - a motion estimation unit for locally and/or globally estimating motion of the subject based on spatial similarities of pixels or pixel groups over consecutive image frames, - a spatial characteristic extraction unit for globally extracting motion of the subject based on a displacement of a spatial characteristic of a group of pixels exhibiting the same or similar properties, and - a motion characterization unit for determining the type of motion of the subject within said set of image frames as either in-plane or out-of-plane motion by calculating a similarity measure of the similarity of the outputs of said motion estimation unit and said spatial characteristic extraction unit; - a motion estimation unit for locally and/or globally estimating motion of the subject based on spatial similarities of pixels or pixel groups over consecutive image frames, - a spatial characteristic extraction unit for globally extracting motion of the subject based on a displacement of a spatial characteristic of a group of pixels exhibiting the same or similar properties, and - a motion characterization unit for determining the type of motion of the subject within said set of image frames as either in-plane or out-of-plane motion by calculating a similarity measure of the similarity of the outputs of said motion estimation unit and said spatial characteristic extraction unit; - a signal extraction unit for extracting photoplethysmographic, PPG, signals from said set of image frames and configured to use said characterization of motion of the subject within said set of image frames to extract said PPG signals only from image frames showing no or substantially no out-of-plane motion or for replacing parts of said PPG signals extracted from image frames showing out-of-plane motion by interpolated signal parts. or to reduce the size of the at least one measurement area, from which PPG signals are extracted, in case of out-of-plane motion of the subject, in particular to extract PPG signals only from a central area of the at least one measurement area; and - a vital signs determination unit for determining vital sign information from said extracted PPG signals.