Tracker for tracking a target, comprising an image sensor arrangement having an imaging region composed of a plurality of pixels arranged in a matrix of columns and rows; the imaging region being arranged to take an image of a scene including the target; a controller configured to receive or generate a timing signal, the timing signal indicating a time duration during which an illumination unit illuminating the target in the scene is switched on and off, control the imaging region to take an image of the scene when the timing signal indicates that the illumination unit is switched on, and read out a subgroup of neighboring columns or rows constituting a stripe window of the imaging region so that an image section including the target is obtained, control the imaging region to take another image of the scene when the timing signal indicates that the illumination unit is switched off, and read out another subgroup of neighboring columns or rows constituting another stripe window of the imaging region so that another image section including the target is obtained, and calculate a difference image section by determining a difference between the pixel values of the pixels of the image section and the other image section, an output unit configured to output the difference image section so as to identify the target in the difference image section, wherein the imaging region of the image sensor arrangement is adapted so that more pixels are arranged in the direction of the rows than in the directions of the columns and is arranged in the tracker so that the direction of the rows corresponds to the vertical direction. an image sensor arrangement having an imaging region composed of a plurality of pixels arranged in a matrix of columns and rows; the imaging region being arranged to take an image of a scene including the target; a controller configured to receive or generate a timing signal, the timing signal indicating a time duration during which an illumination unit illuminating the target in the scene is switched on and off, control the imaging region to take an image of the scene when the timing signal indicates that the illumination unit is switched on, and read out a subgroup of neighboring columns or rows constituting a stripe window of the imaging region so that an image section including the target is obtained, control the imaging region to take another image of the scene when the timing signal indicates that the illumination unit is switched off, and read out another subgroup of neighboring columns or rows constituting another stripe window of the imaging region so that another image section including the target is obtained, and calculate a difference image section by determining a difference between the pixel values of the pixels of the image section and the other image section, receive or generate a timing signal, the timing signal indicating a time duration during which an illumination unit illuminating the target in the scene is switched on and off, control the imaging region to take an image of the scene when the timing signal indicates that the illumination unit is switched on, and read out a subgroup of neighboring columns or rows constituting a stripe window of the imaging region so that an image section including the target is obtained, control the imaging region to take another image of the scene when the timing signal indicates that the illumination unit is switched off, and read out another subgroup of neighboring columns or rows constituting another stripe window of the imaging region so that another image section including the target is obtained, and calculate a difference image section by determining a difference between the pixel values of the pixels of the image section and the other image section, an output unit configured to output the difference image section so as to identify the target in the difference image section, wherein the imaging region of the image sensor arrangement is adapted so that more pixels are arranged in the direction of the rows than in the directions of the columns and is arranged in the tracker so that the direction of the rows corresponds to the vertical direction.