Gap Framework - Natural Language Processing for PDF/TIFF/Image Documents

SEGMENTATION MODULE

High Precision Document Segmentation
Technical Specification, Gap v0.9.2

1 Segment

1.1 Segment Overview

The segment NLP preprocessor contains the following primary classes, and their relationships:

  • Segment - This is the base class for the representation of a Natural Language Processed text segmented into human perceived text layout, such as headings, paragraphs, table columns, etc. The constructor takes as a parameter a text to segment.
segments = Segment(text)

segment_relationships

Fig. 1a High Level view of Segment Class Object Relationships  

1.2 Segment Initializer (Constructor)

Synopsis

Segment(text=None)

Parameters

text: A Unicode text string.

Usage

When specified without parameters, an empty Segments object is created.

Otherwise, the text sequence is analyzed for region detection based on whitespace surrounding the text.

Regions include:

  • Headings
  • Paragraphs
  • Page Numbering

Exceptions

A TypeError is raised if the type of the parameter is not the expected type.

1.3 Segment Properties

1.3.1 segments

Synopsis

# Getter
segments = segment.segments

Usage

When used as a getter the property returns REWRITE IN PROGRESS.

1.4 Segment Overridden Operators

1.4.1 len()

Synopsis

nsegments = len(segment)

Usage

The len() (__len__) operator is overridden to return the number of Image objects in the collection.

1.4.1 []

Synopsis

image = images[n]

Usage

The [] (__getitem__) operator is overridden to return the segment at the specified index.

Exceptions

A IndexError is raised if the index is out of range.

1.5 Segment Private Methods

The segment class contains the following private methods:

  • _segmentation() – This method is called by the constructor. It parses the text to identify text layouts, such as headings, paragraphs, columns, page numbering, etc, and separates the text into segments according to the identified layout.

1.6 Segment Public Methods

The Segment class contains of following public methods:

  • There are no public methods.

APPENDIX I: Updates

Pre-Gap (Epipog) v1.4
+ An initial prototype was built

Gap v0.91 (alpha)
+ Rewrite of Specification

APPENDIX II: Anticipated Engineering

The following has been identified as enhancement/issues to be addressed in subsequent update:

  1. Add support for splitting dual column pages.

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