CS294-9: Document Image Analysis

R. Fateman and H. Baird

Fall, 2000

University of California at Berkeley

Assignment 1. Due Sept. 11, 2000

Readings: the preface to chapter 4 in the O’Gorman/Kasturi collection, and the papers by Mori and by Tsujimoto. The latter two are available on-line in the class papers subdirectory as pdf files: mori92.pdf and tsuji92.pdf. Please do this RIGHT NOW, not when the assignment is due. If you have trouble accessing them (we are trying to comply with copyright by password protecting them), tell us.

In the images subdirectory http://www.cs.berkeley.edu/~fateman/294-9/images read the file README.

The filenames ending in “.tif” are in tagged image format, and can be displayed by various image-aware programs. See if you can find at least one on your favorite computer. Photoshop is the high-priced program, but freeware digital image software should work. A standard installation of Windows NT comes with Imaging from Eastman software. It can read and write tiff images. On UNIX, xv should work. Various Microsoft Office programs seems to know about “tiff” format images as well.

b. Make a hard-copy printout of numbers.tif to a printer of your choice.

c. Extract the image of the numeral 2 in the README file. Write a brief program in your favorite programming language that can convert between this “ascii” version of the representation and some run-length encoded version. The file two.lisp has two such encodings. Yours need not be exactly the same. Show that your transformation is reversible.

d. There are a number of free OCR systems available. For example, WOCAR, GOCR, Fineweb, as well as a number of proprietary commercial OCR systems at various prices. Generally an entry-level version of some such system comes with a page scanner, even those priced at the sub-$100 level. Tell us if you have a working version of one of these systems, and if possible, run it on the files numbers.tif and page35.tif. If you don’t have access to such a system, that’s ok too.

e. Why do you suppose that Norbert Weiner, by all accounts a very smart person, considered that optical character recognition was a solved problem circa 1945?

(Write a paragraph or two.)

f. All current attempts to do OCR use separate sequential stages of processing, as described in the readings. It has become apparent to developers of OCR software that very high accuracy depends critically on broad and effective communication between the stages, and not just in the “forward” direction. Perhaps one can do better by abandoning this paradigm. Can you think of a way of doing OCR without this separation? Could you, say, decode an image by using a web-based search engine? (Write a paragraph or two.)