Abstract: A method and associated apparatus are disclosed for scanning documents and producing electronically stored signals corresponding to images on the documents. A stripe pattern of lines obliquely inclined relative to the direction of document movement provides precise indications of "pel" increments of document displacement relative to the image sensing apparatus. Using these indications, the system is effectively rendered insensitive to interruptions of document motion and/or variations in document motion speed. For example, this enables a system having limit buffer storage capacity to capture a full document image; by intermittently scanning portions of the image which fill the store, and halting document motion between scans of successive portions to allow for processing of the partial image data between the buffer store and other parts of the system's memory.