A television signal receiver processes a television signal representing a letterbox image display format with a main image region, and a bar region containing auxiliary "helper" information to help convert from interlaced to progressive scanning. In the presence of image motion, a main image component and the helper component are combined and conveyed to a video processor. In the absence of motion, other image information, e.g., field repeated information, is conveyed to the video processor. The information conveyed to the video processor is determined by a switching network responsive to an control signal from a motion detector which senses low frequency luminance image information substantially exclusive of high frequency image information.