A toy system, the toy system comprising a data processing system and one or more toys, the one or more toys including at least one reference toy (440, 540, 740, 1040) having a visual appearance recognisable by the data processing system in a captured image of a real-world scene including said at least one reference toy (440, 540, 740, 1040), the data processing system comprising an image capturing device, a processing unit, and a display, wherein the data processing system has stored thereon information associated with the at least one reference toy (440, 540, 740, 1040), the information including at least one predetermined reference position (1043A-C) defined relative to the at least one reference toy (440, 540, 740, 1040); and wherein the data processing system is configured to: • capture a sequence of images of a real-world scene, the real-world scene including said at least one reference toy (440, 540, 740, 1040); • process the captured images to detect and recognize said at least one reference toy (440, 540, 740, 1040) within the real-world scene; • retrieve the at least one predetermined reference position (1043A-C) from the stored information associated with the recognized at least on reference toy (440, 540, 740, 1040); • process the captured images to identify the at least one predetermined reference position (1043A-C) within at least a first image of the sequence of captured images; • responsive to detecting a user manipulation, generate and render computer-generated perceptual information associated with the detected user manipulation; characterized in that the data processing system is configured to » selectively process a sub-image (542, 742, 1042A-C) within the first image, the sub-image (542, 742, 1042A-C) depicting said identified reference position (1043A-C), wherein the sub-image (542, 742, 1042A-C) has a shape and size smaller than the first image, to selectively detect the user manipulation of the real-world scene at the identified at least one predetermined reference position (1043A-C). • capture a sequence of images of a real-world scene, the real-world scene including said at least one reference toy (440, 540, 740, 1040); • process the captured images to detect and recognize said at least one reference toy (440, 540, 740, 1040) within the real-world scene; • retrieve the at least one predetermined reference position (1043A-C) from the stored information associated with the recognized at least on reference toy (440, 540, 740, 1040); • process the captured images to identify the at least one predetermined reference position (1043A-C) within at least a first image of the sequence of captured images; • responsive to detecting a user manipulation, generate and render computer-generated perceptual information associated with the detected user manipulation; » selectively process a sub-image (542, 742, 1042A-C) within the first image, the sub-image (542, 742, 1042A-C) depicting said identified reference position (1043A-C), wherein the sub-image (542, 742, 1042A-C) has a shape and size smaller than the first image, to selectively detect the user manipulation of the real-world scene at the identified at least one predetermined reference position (1043A-C).