A computer peripheral that may operate as a scanner. The scanner captures image frames as it is moved across an object. The image frames are formed into a composite image based on computations in two processes. In a first process, fast track processing determines a coarse position of each of the image frames based on a relative position between each successive image frame and a respective preceding image determine by matching overlapping portions of the image frames. In a second process, fine position adjustments are computed to reduce inconsistencies from determining positions of image frames based on relative positions to multiple prior image frames. Processing of the image frames may allow a scan of an object to be suspended and resumed automatically when a user lifts the scanner, by deleting out of focus image frames and matching subsequent image frames to previously stored image frames.