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254 lines
12 KiB
C++
254 lines
12 KiB
C++
///////////////////////////////////////////////////////////////////////
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// File: colpartitiongrid.h
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// Description: Class collecting code that acts on a BBGrid of ColPartitions.
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// Author: Ray Smith
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// Created: Mon Oct 05 08:42:01 PDT 2009
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//
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// (C) Copyright 2009, Google Inc.
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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///////////////////////////////////////////////////////////////////////
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#ifndef TESSERACT_TEXTORD_COLPARTITIONGRID_H_
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#define TESSERACT_TEXTORD_COLPARTITIONGRID_H_
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#include "bbgrid.h"
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#include "colpartition.h"
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#include "colpartitionset.h"
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namespace tesseract {
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class TabFind;
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// ColPartitionGrid is a BBGrid of ColPartition.
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// It collects functions that work on the grid.
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class ColPartitionGrid : public BBGrid<ColPartition,
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ColPartition_CLIST,
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ColPartition_C_IT> {
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public:
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ColPartitionGrid() = default;
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ColPartitionGrid(int gridsize, const ICOORD& bleft, const ICOORD& tright);
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virtual ~ColPartitionGrid() = default;
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// Handles a click event in a display window.
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void HandleClick(int x, int y);
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// Merges ColPartitions in the grid that look like they belong in the same
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// textline.
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// For all partitions in the grid, calls the box_cb permanent callback
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// to compute the search box, searches the box, and if a candidate is found,
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// calls the confirm_cb to check any more rules. If the confirm_cb returns
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// true, then the partitions are merged.
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// Both callbacks are deleted before returning.
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void Merges(TessResultCallback2<bool, ColPartition*, TBOX*>* box_cb,
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TessResultCallback2<bool, const ColPartition*,
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const ColPartition*>* confirm_cb);
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// For the given partition, calls the box_cb permanent callback
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// to compute the search box, searches the box, and if a candidate is found,
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// calls the confirm_cb to check any more rules. If the confirm_cb returns
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// true, then the partitions are merged.
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// Returns true if the partition is consumed by one or more merges.
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bool MergePart(TessResultCallback2<bool, ColPartition*, TBOX*>* box_cb,
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TessResultCallback2<bool, const ColPartition*,
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const ColPartition*>* confirm_cb,
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ColPartition* part);
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// Computes and returns the total overlap of all partitions in the grid.
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// If overlap_grid is non-null, it is filled with a grid that holds empty
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// partitions representing the union of all overlapped partitions.
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int ComputeTotalOverlap(ColPartitionGrid** overlap_grid);
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// Finds all the ColPartitions in the grid that overlap with the given
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// box and returns them SortByBoxLeft(ed) and uniqued in the given list.
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// Any partition equal to not_this (may be nullptr) is excluded.
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void FindOverlappingPartitions(const TBOX& box, const ColPartition* not_this,
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ColPartition_CLIST* parts);
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// Finds and returns the best candidate ColPartition to merge with part,
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// selected from the candidates list, based on the minimum increase in
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// pairwise overlap among all the partitions overlapped by the combined box.
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// If overlap_increase is not nullptr then it returns the increase in overlap
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// that would result from the merge.
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// See colpartitiongrid.cpp for a diagram.
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ColPartition* BestMergeCandidate(
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const ColPartition* part, ColPartition_CLIST* candidates, bool debug,
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TessResultCallback2<bool, const ColPartition*,
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const ColPartition*>* confirm_cb,
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int* overlap_increase);
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// Split partitions where it reduces overlap between their bounding boxes.
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// ColPartitions are after all supposed to be a partitioning of the blobs
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// AND of the space on the page!
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// Blobs that cause overlaps get removed, put in individual partitions
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// and added to the big_parts list. They are most likely characters on
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// 2 textlines that touch, or something big like a dropcap.
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void SplitOverlappingPartitions(ColPartition_LIST* big_parts);
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// Filters partitions of source_type by looking at local neighbours.
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// Where a majority of neighbours have a text type, the partitions are
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// changed to text, where the neighbours have image type, they are changed
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// to image, and partitions that have no definite neighbourhood type are
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// left unchanged.
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// im_box and rerotation are used to map blob coordinates onto the
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// nontext_map, which is used to prevent the spread of text neighbourhoods
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// into images.
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// Returns true if anything was changed.
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bool GridSmoothNeighbours(BlobTextFlowType source_type, Pix* nontext_map,
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const TBOX& im_box, const FCOORD& rerotation);
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// Reflects the grid and its colpartitions in the y-axis, assuming that
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// all blob boxes have already been done.
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void ReflectInYAxis();
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// Rotates the grid and its colpartitions by the given angle, assuming that
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// all blob boxes have already been done.
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void Deskew(const FCOORD& deskew);
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// Transforms the grid of partitions to the output blocks, putting each
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// partition into a separate block. We don't really care about the order,
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// as we just want to get as much text as possible without trying to organize
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// it into proper blocks or columns.
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void ExtractPartitionsAsBlocks(BLOCK_LIST* blocks, TO_BLOCK_LIST* to_blocks);
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// Sets the left and right tabs of the partitions in the grid.
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void SetTabStops(TabFind* tabgrid);
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// Makes the ColPartSets and puts them in the PartSetVector ready
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// for finding column bounds. Returns false if no partitions were found.
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// Each ColPartition in the grid is placed in a single ColPartSet based
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// on the bottom-left of its bounding box.
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bool MakeColPartSets(PartSetVector* part_sets);
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// Makes a single ColPartitionSet consisting of a single ColPartition that
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// represents the total horizontal extent of the significant content on the
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// page. Used for the single column setting in place of automatic detection.
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// Returns nullptr if the page is empty of significant content.
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ColPartitionSet* MakeSingleColumnSet(WidthCallback* cb);
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// Mark the BLOBNBOXes in each partition as being owned by that partition.
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void ClaimBoxes();
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// Retypes all the blobs referenced by the partitions in the grid.
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// Image blobs are sliced on the grid boundaries to give the tab finder
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// a better handle on the edges of the images, and the actual blobs are
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// returned in the im_blobs list, as they are not owned by the block.
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void ReTypeBlobs(BLOBNBOX_LIST* im_blobs);
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// The boxes within the partitions have changed (by deskew) so recompute
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// the bounds of all the partitions and reinsert them into the grid.
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void RecomputeBounds(int gridsize, const ICOORD& bleft,
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const ICOORD& tright, const ICOORD& vertical);
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// Improves the margins of the ColPartitions in the grid by calling
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// FindPartitionMargins on each.
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void GridFindMargins(ColPartitionSet** best_columns);
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// Improves the margins of the ColPartitions in the list by calling
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// FindPartitionMargins on each.
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void ListFindMargins(ColPartitionSet** best_columns,
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ColPartition_LIST* parts);
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// Deletes all the partitions in the grid after disowning all the blobs.
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void DeleteParts();
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// Deletes all the partitions in the grid that are of type BRT_UNKNOWN and
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// all the blobs in them.
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void DeleteUnknownParts(TO_BLOCK* block);
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// Deletes all the partitions in the grid that are NOT of flow type
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// BTFT_LEADER.
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void DeleteNonLeaderParts();
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// Finds and marks text partitions that represent figure captions.
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void FindFigureCaptions();
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//////// Functions that manipulate ColPartitions in the grid ///////
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//////// to find chains of partner partitions of the same type. ///////
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// For every ColPartition in the grid, finds its upper and lower neighbours.
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void FindPartitionPartners();
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// Finds the best partner in the given direction for the given partition.
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// Stores the result with AddPartner.
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void FindPartitionPartners(bool upper, ColPartition* part);
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// Finds the best partner in the given direction for the given partition.
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// Stores the result with AddPartner.
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void FindVPartitionPartners(bool to_the_left, ColPartition* part);
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// For every ColPartition with multiple partners in the grid, reduces the
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// number of partners to 0 or 1. If get_desperate is true, goes to more
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// desperate merge methods to merge flowing text before breaking partnerships.
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void RefinePartitionPartners(bool get_desperate);
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private:
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// Finds and returns a list of candidate ColPartitions to merge with part.
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// The candidates must overlap search_box, and when merged must not
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// overlap any other partitions that are not overlapped by each individually.
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void FindMergeCandidates(const ColPartition* part, const TBOX& search_box,
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bool debug, ColPartition_CLIST* candidates);
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// Smoothes the region type/flow type of the given part by looking at local
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// neighbours and the given image mask. Searches a padded rectangle with the
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// padding truncated on one size of the part's box in turn for each side,
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// using the result (if any) that has the least distance to all neighbours
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// that contribute to the decision. This biases in favor of rectangular
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// regions without completely enforcing them.
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// If a good decision cannot be reached, the part is left unchanged.
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// im_box and rerotation are used to map blob coordinates onto the
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// nontext_map, which is used to prevent the spread of text neighbourhoods
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// into images.
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// Returns true if the partition was changed.
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bool SmoothRegionType(Pix* nontext_map,
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const TBOX& im_box,
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const FCOORD& rerotation,
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bool debug,
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ColPartition* part);
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// Executes the search for SmoothRegionType in a single direction.
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// Creates a bounding box that is padded in all directions except direction,
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// and searches it for other partitions. Finds the nearest collection of
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// partitions that makes a decisive result (if any) and returns the type
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// and the distance of the collection. If there are any pixels in the
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// nontext_map, then the decision is biased towards image.
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BlobRegionType SmoothInOneDirection(BlobNeighbourDir direction,
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Pix* nontext_map,
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const TBOX& im_box,
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const FCOORD& rerotation,
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bool debug,
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const ColPartition& part,
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int* best_distance);
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// Counts the partitions in the given search_box by appending the gap
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// distance (scaled by dist_scaling) of the part from the base_part to the
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// vector of the appropriate type for the partition. Prior to return, the
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// vectors in the dists array are sorted in increasing order.
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// dists must be an array of GenericVectors of size NPT_COUNT.
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void AccumulatePartDistances(const ColPartition& base_part,
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const ICOORD& dist_scaling,
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const TBOX& search_box,
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Pix* nontext_map,
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const TBOX& im_box,
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const FCOORD& rerotation,
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bool debug,
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GenericVector<int>* dists);
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// Improves the margins of the ColPartition by searching for
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// neighbours that vertically overlap significantly.
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void FindPartitionMargins(ColPartitionSet* columns, ColPartition* part);
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// Starting at x, and going in the specified direction, up to x_limit, finds
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// the margin for the given y range by searching sideways,
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// and ignoring not_this.
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int FindMargin(int x, bool right_to_left, int x_limit,
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int y_bottom, int y_top, const ColPartition* not_this);
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};
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} // namespace tesseract.
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#endif // TESSERACT_TEXTORD_COLPARTITIONGRID_H_
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