According to an aspect, there is provided an apparatus for determining a pulse signal from a video sequence, the apparatus comprising a processing unit configured to obtain a video sequence, the video sequence comprising a plurality of image frames form a plurality of video sub-sequences, each video sub-sequence comprising a frame segment from each image frame in a subset of the image frames, wherein each image frame is divided into a plurality of frame segments for a first video sub-sequence formed from frame segments from a first subset of image frames, comparing a representative value for the first video sub-sequence to representative values for video sub-sequences formed from frame segments from a second subset of image frames concatenate the first video sub-sequence to a second video sub-sequence formed from frame segments from the second subset of image frames based on the comparison of representative values and determine a pulse signal from the concatenated video sub-sequences.
