Laserfiche Clinic 2006-2007Laserfiche Clinic 2006-2007

Liaison Luncheon @ HMC, Sept. 12Liaison Luncheon @ HMC, Sept. 12thth, 2006, 2006

Adam FieldAdam Field

Stephen SmithStephen Smith

Ben Tribelhorn, PMBen Tribelhorn, PM

Aaron WolinAaron Wolin

Advisor:Advisor:

Zach DoddsZach Dodds

The Problem

To convert pictures of documents taken with a digital camera into images that can be organized using Laserfiche's OCR and database technologies.

Project goal:

raw image OCR-able image

The Problem

To convert pictures of documents taken with a digital camera into images that can be organized using Laserfiche's OCR and database technologies.

Project goal:

Some important cases:

• presence of paperclips and/or staples• varied/confusing backgrounds (including stacks of papers)• one or more edges off the edge of the image• knowing when the system has failed• camera perspective issues - documents not images head-on (?) • other important cases?

raw image OCR-able image

Approach taken by previous clinic• Finding document corners• Unwarping to 8.5 x 11"

Possible approach taken by current clinic• First analyzing text-line boundaries• Then unwarping to straighten them

ApproachesApproachesOutside -

InInside -

Out

?

Lu and Tan. “Camera Document Restoration for OCR.” http://www.m.cs.osakafu-u.ac.jp/cbdar/proceedings/papers/O1-3.pdf

VSBs

Camera Document Restoration for OCRCamera Document Restoration for OCR

• Several algorithms use VSBs to detect and correct the image

• Able to detect the type of distortion or severity of the warping

• Uses “Vertical Stroke Boundaries” VSBs of characters

Lu, Chen, and Ko. “Perspective rectification of document images usingfuzzy set and morphological operations.” http://vlab.ee.nus.edu.sg/~bmchen/papers/ivc.pdf

Tip point tracing process.

Finding Vertical Stroke BoundariesFinding Vertical Stroke Boundaries

•Connected components first

• Find the "top" and "base" lines for a line of text

• Scan between the top and base lines, searching for pixels that form relatively orthogonal and straight lines

Avila and Lins. “A Fast Orientation and Skew Detection Algorithm for Monochromatic Document Images.” http://delivery.acm.org/10.1145/1100000/1096631/p118-avila.pdf

A Fast Orientation and Skew A Fast Orientation and Skew Detection AlgorithmDetection Algorithm

• Uses connected components and nearest neighbors to find document skew

• Places the text line angles into two histograms from ±90º Precisions are 1.0º and 0.1º

• The skew angle is the histogram peak

Hand-writing

GeometricPerspectiveSkew

Magazines/

Newspaper

Forms

Problem TaxonomyProblem Taxonomy

Mostly text documents

warp severity

document difficulty

Hand-writing

GeometricPerspectiveSkew

Magazines/

Newspaper

Forms

Problem Priorities Problem Priorities ??

Mostly text documents

primary focus

secondary focus

warp severity

document difficulty

Pair 1's planPair 1's plan

Finding character strokes

Estimating warp severity

Thresholding

picture fromben and stephen

Least-sq. line-fitting

Visualizing the processing

Finding skew estimates

Two-tier assessment 1) reasonable? 2) OCR accuracy

picture fromaaron & adam

Pair 2's planPair 2's plan

Tentative ScheduleTentative Schedule

Weekly conference calls with Ed Heaney

Accessible codebase and performance updates

Other deliverables ?

Th 9/21 (11:30 am) Call - progress update

T 9/26 Initial presentation @ Harvey Mudd

Th 9/28 Prototype of each algorithm

F 10/6 ? Site visit and presentation @ Laserfiche

Comments?Comments?

Other PapersOther Papers

HandWriting

Image WarpingGeometricPerspectiveSkew

Magazines

Forms

Plain Text

Hand-writing

GeometricPerspectiveSkew

Magazines/

Newspaper

Forms

TaxonomyTaxonomy

Mostly text

documents