tesseract/ccmain/paragraphs.h
david.eger@gmail.com eeeb4f513c Provide better paragraph segmentation without having to run fully
automatic layout analysis.



git-svn-id: https://tesseract-ocr.googlecode.com/svn/trunk@725 d0cd1f9f-072b-0410-8dd7-cf729c803f20
2012-05-10 00:03:34 +00:00

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4.4 KiB
C++

/**********************************************************************
* File: paragraphs.h
* Description: Paragraph Detection data structures.
* Author: David Eger
* Created: 25 February 2011
*
* (C) Copyright 2011, Google Inc.
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
** http://www.apache.org/licenses/LICENSE-2.0
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*
**********************************************************************/
#ifndef TESSERACT_CCMAIN_PARAGRAPHS_H_
#define TESSERACT_CCMAIN_PARAGRAPHS_H_
#include "rect.h"
#include "ocrpara.h"
#include "genericvector.h"
#include "strngs.h"
class WERD;
class UNICHARSET;
namespace tesseract {
class MutableIterator;
// This structure captures all information needed about a text line for the
// purposes of paragraph detection. It is meant to be exceedingly light-weight
// so that we can easily test paragraph detection independent of the rest of
// Tesseract.
class RowInfo {
public:
// Constant data derived from Tesseract output.
STRING text; // the full UTF-8 text of the line.
bool ltr; // whether the majority of the text is left-to-right
// TODO(eger) make this more fine-grained.
bool has_leaders; // does the line contain leader dots (.....)?
bool has_drop_cap; // does the line have a drop cap?
int pix_ldistance; // distance to the left pblock boundary in pixels
int pix_rdistance; // distance to the right pblock boundary in pixels
float pix_xheight; // guessed xheight for the line
int average_interword_space; // average space between words in pixels.
int num_words;
TBOX lword_box; // in normalized (horiz text rows) space
TBOX rword_box; // in normalized (horiz text rows) space
STRING lword_text; // the UTF-8 text of the leftmost werd
STRING rword_text; // the UTF-8 text of the rightmost werd
// The text of a paragraph typically starts with the start of an idea and
// ends with the end of an idea. Here we define paragraph as something that
// may have a first line indent and a body indent which may be different.
// Typical words that start an idea are:
// 1. Words in western scripts that start with
// a capital letter, for example "The"
// 2. Bulleted or numbered list items, for
// example "2."
// Typical words which end an idea are words ending in punctuation marks. In
// this vocabulary, each list item is represented as a paragraph.
bool lword_indicates_list_item;
bool lword_likely_starts_idea;
bool lword_likely_ends_idea;
bool rword_indicates_list_item;
bool rword_likely_starts_idea;
bool rword_likely_ends_idea;
};
// Main entry point for Paragraph Detection Algorithm.
//
// Given a set of equally spaced textlines (described by row_infos),
// Split them into paragraphs. See http://goto/paragraphstalk
//
// Output:
// row_owners - one pointer for each row, to the paragraph it belongs to.
// paragraphs - this is the actual list of PARA objects.
// models - the list of paragraph models referenced by the PARA objects.
// caller is responsible for deleting the models.
void DetectParagraphs(int debug_level,
GenericVector<RowInfo> *row_infos,
GenericVector<PARA *> *row_owners,
PARA_LIST *paragraphs,
GenericVector<ParagraphModel *> *models);
// Given a MutableIterator to the start of a block, run DetectParagraphs on
// that block and commit the results to the underlying ROW and BLOCK structs,
// saving the ParagraphModels in models. Caller owns the models.
// We use unicharset during the function to answer questions such as "is the
// first letter of this word upper case?"
void DetectParagraphs(int debug_level,
bool after_text_recognition,
const MutableIterator *block_start,
GenericVector<ParagraphModel *> *models);
} // namespace
#endif // TESSERACT_CCMAIN_PARAGRAPHS_H_