1. In an optical scanning system having an optical scanning head for sequentially scanning horizontally across a document to create pixel oriented data representing text of the document for subsequent comparison searching to determine the alpha-numeric contents of the document, the improvement for automatically compensating for text line skew comprising: (a) means for dividing the data into equal swaths representing vertical columns on the documents; (b) means for scanning the data by swath to determine the apparent text line initiations and termination contained therein and for creating a data matrix of initiation/termination pairs by swath; said data matrix having at least left and right boundaries; (c) means for sequentially searching the data in the data matrix left and right for each pair in a base vector swath, representative of a predetermined range of apparent text line initiations and terminations, to trace the data indicative of apparent text lines to determine a plurality of points apparently on base lines of respective ones of the apparent text lines of the document; (d) means for determining the apparent skew angle of the text from the points on the apparent base lines; and; (e) means for bounding the data of the apparent text lines for subsequent comparison searching from the found intersection/termination pairs and apparent skew angle determined.