tesseract/textord/colpartitiongrid.h

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///////////////////////////////////////////////////////////////////////
// File: colpartitionrid.h
// Description: Class collecting code that acts on a BBGrid of ColPartitions.
// Author: Ray Smith
// Created: Mon Oct 05 08:42:01 PDT 2009
//
// (C) Copyright 2009, 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_TEXTORD_COLPARTITIONGRID_H_
#define TESSERACT_TEXTORD_COLPARTITIONGRID_H_
#include "bbgrid.h"
#include "colpartition.h"
#include "colpartitionset.h"
namespace tesseract {
class TabFind;
// ColPartitionGrid is a BBGrid of ColPartition.
// It collects functions that work on the grid.
class ColPartitionGrid : public BBGrid<ColPartition,
ColPartition_CLIST,
ColPartition_C_IT> {
public:
ColPartitionGrid();
ColPartitionGrid(int gridsize, const ICOORD& bleft, const ICOORD& tright);
virtual ~ColPartitionGrid();
// Handles a click event in a display window.
void HandleClick(int x, int y);
// Merges ColPartitions in the grid that look like they belong in the same
// textline.
// For all partitions in the grid, calls the box_cb permanent callback
// to compute the search box, searches the box, and if a candidate is found,
// calls the confirm_cb to check any more rules. If the confirm_cb returns
// true, then the partitions are merged.
// Both callbacks are deleted before returning.
void Merges(TessResultCallback2<bool, ColPartition*, TBOX*>* box_cb,
TessResultCallback2<bool, const ColPartition*,
const ColPartition*>* confirm_cb);
// For the given partition, calls the box_cb permanent callback
// to compute the search box, searches the box, and if a candidate is found,
// calls the confirm_cb to check any more rules. If the confirm_cb returns
// true, then the partitions are merged.
// Returns true if the partition is consumed by one or more merges.
bool MergePart(TessResultCallback2<bool, ColPartition*, TBOX*>* box_cb,
TessResultCallback2<bool, const ColPartition*,
const ColPartition*>* confirm_cb,
ColPartition* part);
// Computes and returns the total overlap of all partitions in the grid.
// If overlap_grid is non-null, it is filled with a grid that holds empty
// partitions representing the union of all overlapped partitions.
int ComputeTotalOverlap(ColPartitionGrid** overlap_grid);
// Finds all the ColPartitions in the grid that overlap with the given
// box and returns them SortByBoxLeft(ed) and uniqued in the given list.
// Any partition equal to not_this (may be NULL) is excluded.
void FindOverlappingPartitions(const TBOX& box, const ColPartition* not_this,
ColPartition_CLIST* parts);
// Finds and returns the best candidate ColPartition to merge with part,
// selected from the candidates list, based on the minimum increase in
// pairwise overlap among all the partitions overlapped by the combined box.
// If overlap_increase is not NULL then it returns the increase in overlap
// that would result from the merge.
// See colpartitiongrid.cpp for a diagram.
ColPartition* BestMergeCandidate(
const ColPartition* part, ColPartition_CLIST* candidates, bool debug,
TessResultCallback2<bool, const ColPartition*,
const ColPartition*>* confirm_cb,
int* overlap_increase);
// Split partitions where it reduces overlap between their bounding boxes.
// ColPartitions are after all supposed to be a partitioning of the blobs
// AND of the space on the page!
// Blobs that cause overlaps get removed, put in individual partitions
// and added to the big_parts list. They are most likely characters on
// 2 textlines that touch, or something big like a dropcap.
void SplitOverlappingPartitions(ColPartition_LIST* big_parts);
// Filters partitions of source_type by looking at local neighbours.
// Where a majority of neighbours have a text type, the partitions are
// changed to text, where the neighbours have image type, they are changed
// to image, and partitions that have no definite neighbourhood type are
// left unchanged.
// im_box and rerotation are used to map blob coordinates onto the
// nontext_map, which is used to prevent the spread of text neighbourhoods
// into images.
// Returns true if anything was changed.
bool GridSmoothNeighbours(BlobTextFlowType source_type, Pix* nontext_map,
const TBOX& im_box, const FCOORD& rerotation);
// Compute the mean RGB of the light and dark pixels in each ColPartition
// and also the rms error in the linearity of color.
void ComputePartitionColors(Pix* scaled_color, int scaled_factor,
const FCOORD& rerotation);
// Reflects the grid and its colpartitions in the y-axis, assuming that
// all blob boxes have already been done.
void ReflectInYAxis();
// Rotates the grid and its colpartitions by the given angle, assuming that
// all blob boxes have already been done.
void Deskew(const FCOORD& deskew);
// Transforms the grid of partitions to the output blocks, putting each
// partition into a separate block. We don't really care about the order,
// as we just want to get as much text as possible without trying to organize
// it into proper blocks or columns.
void ExtractPartitionsAsBlocks(BLOCK_LIST* blocks, TO_BLOCK_LIST* to_blocks);
// Sets the left and right tabs of the partitions in the grid.
void SetTabStops(TabFind* tabgrid);
// Makes the ColPartSets and puts them in the PartSetVector ready
// for finding column bounds. Returns false if no partitions were found.
// Each ColPartition in the grid is placed in a single ColPartSet based
// on the bottom-left of its bounding box.
bool MakeColPartSets(PartSetVector* part_sets);
// Makes a single ColPartitionSet consisting of a single ColPartition that
// represents the total horizontal extent of the significant content on the
// page. Used for the single column setting in place of automatic detection.
// Returns NULL if the page is empty of significant content.
ColPartitionSet* MakeSingleColumnSet(WidthCallback* cb);
// Mark the BLOBNBOXes in each partition as being owned by that partition.
void ClaimBoxes();
// Retypes all the blobs referenced by the partitions in the grid.
// Image blobs are sliced on the grid boundaries to give the tab finder
// a better handle on the edges of the images, and the actual blobs are
// returned in the im_blobs list, as they are not owned by the block.
void ReTypeBlobs(BLOBNBOX_LIST* im_blobs);
// The boxes within the partitions have changed (by deskew) so recompute
// the bounds of all the partitions and reinsert them into the grid.
void RecomputeBounds(int gridsize, const ICOORD& bleft,
const ICOORD& tright, const ICOORD& vertical);
// Improves the margins of the ColPartitions in the grid by calling
// FindPartitionMargins on each.
void GridFindMargins(ColPartitionSet** best_columns);
// Improves the margins of the ColPartitions in the list by calling
// FindPartitionMargins on each.
void ListFindMargins(ColPartitionSet** best_columns,
ColPartition_LIST* parts);
// Deletes all the partitions in the grid after disowning all the blobs.
void DeleteParts();
// Deletes all the partitions in the grid that are of type BRT_UNKNOWN and
// all the blobs in them.
void DeleteUnknownParts(TO_BLOCK* block);
// Deletes all the partitions in the grid that are NOT of flow type
// BTFT_LEADER.
void DeleteNonLeaderParts();
// Finds and marks text partitions that represent figure captions.
void FindFigureCaptions();
//////// Functions that manipulate ColPartitions in the grid ///////
//////// to find chains of partner partitions of the same type. ///////
// For every ColPartition in the grid, finds its upper and lower neighbours.
void FindPartitionPartners();
// Finds the best partner in the given direction for the given partition.
// Stores the result with AddPartner.
void FindPartitionPartners(bool upper, ColPartition* part);
// Finds the best partner in the given direction for the given partition.
// Stores the result with AddPartner.
void FindVPartitionPartners(bool to_the_left, ColPartition* part);
// For every ColPartition with multiple partners in the grid, reduces the
// number of partners to 0 or 1. If get_desperate is true, goes to more
// desperate merge methods to merge flowing text before breaking partnerships.
void RefinePartitionPartners(bool get_desperate);
private:
// Finds and returns a list of candidate ColPartitions to merge with part.
// The candidates must overlap search_box, and when merged must not
// overlap any other partitions that are not overlapped by each individually.
void FindMergeCandidates(const ColPartition* part, const TBOX& search_box,
bool debug, ColPartition_CLIST* candidates);
// Smoothes the region type/flow type of the given part by looking at local
// neighbours and the given image mask. Searches a padded rectangle with the
// padding truncated on one size of the part's box in turn for each side,
// using the result (if any) that has the least distance to all neighbours
// that contribute to the decision. This biases in favor of rectangular
// regions without completely enforcing them.
// If a good decision cannot be reached, the part is left unchanged.
// im_box and rerotation are used to map blob coordinates onto the
// nontext_map, which is used to prevent the spread of text neighbourhoods
// into images.
// Returns true if the partition was changed.
bool SmoothRegionType(Pix* nontext_map,
const TBOX& im_box,
const FCOORD& rerotation,
bool debug,
ColPartition* part);
// Executes the search for SmoothRegionType in a single direction.
// Creates a bounding box that is padded in all directions except direction,
// and searches it for other partitions. Finds the nearest collection of
// partitions that makes a decisive result (if any) and returns the type
// and the distance of the collection. If there are any pixels in the
// nontext_map, then the decision is biased towards image.
BlobRegionType SmoothInOneDirection(BlobNeighbourDir direction,
Pix* nontext_map,
const TBOX& im_box,
const FCOORD& rerotation,
bool debug,
const ColPartition& part,
int* best_distance);
// Counts the partitions in the given search_box by appending the gap
// distance (scaled by dist_scaling) of the part from the base_part to the
// vector of the appropriate type for the partition. Prior to return, the
// vectors in the dists array are sorted in increasing order.
// dists must be an array of GenericVectors of size NPT_COUNT.
void AccumulatePartDistances(const ColPartition& base_part,
const ICOORD& dist_scaling,
const TBOX& search_box,
Pix* nontext_map,
const TBOX& im_box,
const FCOORD& rerotation,
bool debug,
GenericVector<int>* dists);
// Improves the margins of the ColPartition by searching for
// neighbours that vertically overlap significantly.
void FindPartitionMargins(ColPartitionSet* columns, ColPartition* part);
// Starting at x, and going in the specified direction, up to x_limit, finds
// the margin for the given y range by searching sideways,
// and ignoring not_this.
int FindMargin(int x, bool right_to_left, int x_limit,
int y_bottom, int y_top, const ColPartition* not_this);
};
} // namespace tesseract.
#endif // TESSERACT_TEXTORD_COLPARTITIONGRID_H_