An image-processing apparatus, comprising: at least one image processor configured to: segment each image frame in a sequence of image frames into different segmented regions that each correspond to a different super-pixel; compute, based on at least a first image frame and a neighbouring image frame preceding the first image frame in the sequence of image frames, a temporal derivative map for the first image frame including non-zero temporal derivatives corresponding to displaced pixels between the first image frame and the neighbouring image frame preceding the first image frame; detect an articulated object in the first image frame based on the non-zero temporal derivatives in the computed temporal derivative map for the first image frame, the articulated object being in a first motion state in the first image frame in which all portions of the object are in motion; compute a temporal derivative map for a second image frame that succeeds said first image frame in said sequence of image frames based on at least the second image frame and the first image frame, the temporal derivative map for the second image frame including non-zero temporal derivatives corresponding to displaced pixels between the first image frame and the second image frame; detect the articulated object in the second image frame based on the non-zero temporal derivatives in the computed temporal derivative map for the second image frame, the articulated object being in a second motion state in the second image frame in which at least a portion of the articulated object is stationary; construct a first connectivity graph representing a connectivity pattern of a first set of super-pixels of said first image frame, the first connectivity graph identifying adjacent super-pixels in the first set of super-pixels and image properties of each super-pixel in the first set of super-pixels; construct a second connectivity graph representing a connectivity pattern of a second set of super-pixels of said second image frame, the second connectivity graph identifying adjacent super-pixels in the second set of super-pixels and image properties of each super-pixel in the second set of super-pixels; and generate, in the second image frame, a complete object mask of said articulated object in the second motion state including restoring the portion of the articulated object which was stationary in the second motion state based on a comparison between said first connectivity graph and said second connectivity graph. segment each image frame in a sequence of image frames into different segmented regions that each correspond to a different super-pixel; compute, based on at least a first image frame and a neighbouring image frame preceding the first image frame in the sequence of image frames, a temporal derivative map for the first image frame including non-zero temporal derivatives corresponding to displaced pixels between the first image frame and the neighbouring image frame preceding the first image frame; detect an articulated object in the first image frame based on the non-zero temporal derivatives in the computed temporal derivative map for the first image frame, the articulated object being in a first motion state in the first image frame in which all portions of the object are in motion; compute a temporal derivative map for a second image frame that succeeds said first image frame in said sequence of image frames based on at least the second image frame and the first image frame, the temporal derivative map for the second image frame including non-zero temporal derivatives corresponding to displaced pixels between the first image frame and the second image frame; detect the articulated object in the second image frame based on the non-zero temporal derivatives in the computed temporal derivative map for the second image frame, the articulated object being in a second motion state in the second image frame in which at least a portion of the articulated object is stationary; construct a first connectivity graph representing a connectivity pattern of a first set of super-pixels of said first image frame, the first connectivity graph identifying adjacent super-pixels in the first set of super-pixels and image properties of each super-pixel in the first set of super-pixels; construct a second connectivity graph representing a connectivity pattern of a second set of super-pixels of said second image frame, the second connectivity graph identifying adjacent super-pixels in the second set of super-pixels and image properties of each super-pixel in the second set of super-pixels; and generate, in the second image frame, a complete object mask of said articulated object in the second motion state including restoring the portion of the articulated object which was stationary in the second motion state based on a comparison between said first connectivity graph and said second connectivity graph.