A computer-implemented method comprising: obtaining input video frames from among video frames of an input video, wherein the video frames were acquired prior to receiving a shutter press indication and following a receiving of the shutter press indication characterised by: for each input video frame, downsampling the input video frame to generate a downsampled video frame; smoothing the downsampled video frame to generate a smoothed video frame; computing a temporal gradient and a spatial gradient for the smoothed video frame; estimating local motion by computing a local motion vector corresponding to a respective candidate pixel patch from among one or more candidate pixel patches within the smoothed video frame, wherein the local motion vector is based on the spatial gradient and the temporal gradient; estimating global motion by computing a global motion vector corresponding to the smoothed video frame; computing one or more subject motion vectors based on a corresponding local motion vector and the global motion vector; converting the one or more subject motion vectors into a score map; computing an entropy score based on the score map; and mapping the entropy score into a subject motion score corresponding to the smoothed video frame; identifying a number of static frames of the video frames based on the subject motion scores for the video frames; determining that the input video is a static video if a ratio of the number of static frames to a number of the video frames in the input video meets a static frame threshold and determining that the input video is a motion video if the ratio fails to meet the static frame threshold; performing a first operation if the input video is recognized to be the static video, wherein the first operation includes marking the input video as static, retaining a shutter image corresponding to the input video in storage, and deleting the input video from storage; and performing a second operation if the input video is recognized to be the motion video, wherein the second operation includes retaining a shutter image corresponding to the input video and the input video in storage. obtaining input video frames from among video frames of an input video, wherein the video frames were acquired prior to receiving a shutter press indication and following a receiving of the shutter press indication characterised by: for each input video frame, downsampling the input video frame to generate a downsampled video frame; smoothing the downsampled video frame to generate a smoothed video frame; computing a temporal gradient and a spatial gradient for the smoothed video frame; estimating local motion by computing a local motion vector corresponding to a respective candidate pixel patch from among one or more candidate pixel patches within the smoothed video frame, wherein the local motion vector is based on the spatial gradient and the temporal gradient; estimating global motion by computing a global motion vector corresponding to the smoothed video frame; computing one or more subject motion vectors based on a corresponding local motion vector and the global motion vector; converting the one or more subject motion vectors into a score map; computing an entropy score based on the score map; and mapping the entropy score into a subject motion score corresponding to the smoothed video frame; downsampling the input video frame to generate a downsampled video frame; smoothing the downsampled video frame to generate a smoothed video frame; computing a temporal gradient and a spatial gradient for the smoothed video frame; estimating local motion by computing a local motion vector corresponding to a respective candidate pixel patch from among one or more candidate pixel patches within the smoothed video frame, wherein the local motion vector is based on the spatial gradient and the temporal gradient; estimating global motion by computing a global motion vector corresponding to the smoothed video frame; computing one or more subject motion vectors based on a corresponding local motion vector and the global motion vector; converting the one or more subject motion vectors into a score map; computing an entropy score based on the score map; and mapping the entropy score into a subject motion score corresponding to the smoothed video frame; identifying a number of static frames of the video frames based on the subject motion scores for the video frames; determining that the input video is a static video if a ratio of the number of static frames to a number of the video frames in the input video meets a static frame threshold and determining that the input video is a motion video if the ratio fails to meet the static frame threshold; performing a first operation if the input video is recognized to be the static video, wherein the first operation includes marking the input video as static, retaining a shutter image corresponding to the input video in storage, and deleting the input video from storage; and performing a second operation if the input video is recognized to be the motion video, wherein the second operation includes retaining a shutter image corresponding to the input video and the input video in storage.