A palletizer system is described for transferring a object that are conveyed along a conveyor to a rack, the object having a surface, the palletizer system comprising a camera, a robot transfer subsystem and a control module. The camera is configured to generate images of the object as it is being conveyed along the conveyor. The robot transfer subsystem comprises a gripper module mounted on a robot, the robot being configured to move the gripper module, and the gripper module being configured to controllably grip the surface. The gripper module operates in two modes, including a single-object mode in which it grips one object, and a double-object mode in which it grips two objects concurrently The control module is configured to (i) in response to the images generated by the camera, control the robot to, in turn, move the gripper module adjacent the surface(s) in parallel with the object(s) and with approximately the same speed as the object(s) and the gripper module to grip the surface(s); (ii) control the robot and gripper module to remove the object(s) from the conveyor and transfer them to the rack, and (iii) control the gripper module to release the surface(s), thereby to allow the object(s) to be stacked on the rack.