An image-stream windowing method includes capturing, with a camera located at a fixed position and having a fixed field of view, a high-resolution image stream of an object that moves during said capturing. The high-resolution image stream includes a sequence of high-resolution frames. The method also includes determining, for each high-resolution frame of the sequence of high-resolution frames, a respective window, of a sequence of windows corresponding to the sequence of high-resolution frames, that encloses the object within said each high-resolution frame. The size and location of the respective window are determined based at least on the fixed position, the fixed field of view, and a position of the object. The method also includes generating a low-resolution image stream from the high-resolution image stream by cropping said each high-resolution frame with its respective window.