13. A scanned document classification system, comprising: a scanner that scans one or more documents; a memory that stores the one or more documents and stores computer-executable instructions for classifying the one or more documents according to original document type; and a processor that executes the instructions, classifies the one or more documents, and outputs a document type for the one or more scanned documents on a user interface; wherein the memory stores, and the processor executes, instructions for: extracting text in a document page; classifying text objects as a function of text object size; classifying page orientation as a function of statistics of text aspect ratio and neighboring character distance; generating a text column structure index; determining whether the document page was originally created using a slide show presentation application, or one of a word processing application and a spreadsheet application, as a function of one or more of the object size, text size, page orientation classifications, and the text column structure index.
13. A scanned document classification system, comprising: a scanner that scans one or more documents; a memory that stores the one or more documents and stores computer-executable instructions for classifying the one or more documents according to original document type; and a processor that executes the instructions, classifies the one or more documents, and outputs a document type for the one or more scanned documents on a user interface; wherein the memory stores, and the processor executes, instructions for: extracting text in a document page; classifying text objects as a function of text object size; classifying page orientation as a function of statistics of text aspect ratio and neighboring character distance; generating a text column structure index; determining whether the document page was originally created using a slide show presentation application, or one of a word processing application and a spreadsheet application, as a function of one or more of the object size, text size, page orientation classifications, and the text column structure index. 14. The system of claim 13 , wherein: the instructions for extracting text comprise instructions for binarizing and segmenting scanned document bitmaps; and the instructions for classifying text size include instructions for extracting connected components from the binary image and classifying the connected components as normal text, large text, and non-text, according to their sizes.