tesseract 4.1.1
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bbgrid.cpp
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1
2// File: bbgrid.cpp
3// Description: Class to hold BLOBNBOXs in a grid for fast access
4// to neighbours.
5// Author: Ray Smith
6//
7// (C) Copyright 2007, Google Inc.
8// Licensed under the Apache License, Version 2.0 (the "License");
9// you may not use this file except in compliance with the License.
10// You may obtain a copy of the License at
11// http://www.apache.org/licenses/LICENSE-2.0
12// Unless required by applicable law or agreed to in writing, software
13// distributed under the License is distributed on an "AS IS" BASIS,
14// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15// See the License for the specific language governing permissions and
16// limitations under the License.
17//
19
20#include "bbgrid.h"
21#include "helpers.h"
22#include "ocrblock.h"
23
24namespace tesseract {
25
27// BBGrid IMPLEMENTATION.
29GridBase::GridBase(int gridsize, const ICOORD& bleft, const ICOORD& tright) {
31}
32
33// Destructor.
34// It is defined here, so the compiler can create a single vtable
35// instead of weak vtables in every compilation unit.
36GridBase::~GridBase() = default;
37
38// (Re)Initialize the grid. The gridsize is the size in pixels of each cell,
39// and bleft, tright are the bounding box of everything to go in it.
40void GridBase::Init(int gridsize, const ICOORD& bleft, const ICOORD& tright) {
42 bleft_ = bleft;
44 if (gridsize_ == 0)
45 gridsize_ = 1;
46 gridwidth_ = (tright.x() - bleft.x() + gridsize_ - 1) / gridsize_;
47 gridheight_ = (tright.y() - bleft.y() + gridsize_ - 1) / gridsize_;
49}
50
51// Compute the given grid coordinates from image coords.
52void GridBase::GridCoords(int x, int y, int* grid_x, int* grid_y) const {
53 *grid_x = (x - bleft_.x()) / gridsize_;
54 *grid_y = (y - bleft_.y()) / gridsize_;
55 ClipGridCoords(grid_x, grid_y);
56}
57
58// Clip the given grid coordinates to fit within the grid.
59void GridBase::ClipGridCoords(int* x, int* y) const {
60 *x = ClipToRange(*x, 0, gridwidth_ - 1);
61 *y = ClipToRange(*y, 0, gridheight_ - 1);
62}
63
65 grid_ = nullptr;
66}
67
68IntGrid::IntGrid(int gridsize, const ICOORD& bleft, const ICOORD& tright)
69 : grid_(nullptr) {
71}
72
74 delete [] grid_;
75}
76
77// (Re)Initialize the grid. The gridsize is the size in pixels of each cell,
78// and bleft, tright are the bounding box of everything to go in it.
79void IntGrid::Init(int gridsize, const ICOORD& bleft, const ICOORD& tright) {
81 delete [] grid_;
82 grid_ = new int[gridbuckets_];
83 Clear();
84}
85
86// Clear all the ints in the grid to zero.
88 for (int i = 0; i < gridbuckets_; ++i) {
89 grid_[i] = 0;
90 }
91}
92
93// Rotate the grid by rotation, keeping cell contents.
94// rotation must be a multiple of 90 degrees.
95// NOTE: due to partial cells, cell coverage in the rotated grid will be
96// inexact. This is why there is no Rotate for the generic BBGrid.
97// TODO(rays) investigate fixing this inaccuracy by moving the origin after
98// rotation.
99void IntGrid::Rotate(const FCOORD& rotation) {
100 ASSERT_HOST(rotation.x() == 0.0f || rotation.y() == 0.0f);
101 ICOORD old_bleft(bleft());
102 //ICOORD old_tright(tright());
103 int old_width = gridwidth();
104 int old_height = gridheight();
105 TBOX box(bleft(), tright());
106 box.rotate(rotation);
107 int* old_grid = grid_;
108 grid_ = nullptr;
109 Init(gridsize(), box.botleft(), box.topright());
110 // Iterate over the old grid, copying data to the rotated position in the new.
111 int oldi = 0;
112 FCOORD x_step(rotation);
113 x_step *= gridsize();
114 for (int oldy = 0; oldy < old_height; ++oldy) {
115 FCOORD line_pos(old_bleft.x(), old_bleft.y() + gridsize() * oldy);
116 line_pos.rotate(rotation);
117 for (int oldx = 0; oldx < old_width; ++oldx, line_pos += x_step, ++oldi) {
118 int grid_x, grid_y;
119 GridCoords(static_cast<int>(line_pos.x() + 0.5),
120 static_cast<int>(line_pos.y() + 0.5),
121 &grid_x, &grid_y);
122 grid_[grid_y * gridwidth() + grid_x] = old_grid[oldi];
123 }
124 }
125 delete [] old_grid;
126}
127
128// Returns a new IntGrid containing values equal to the sum of all the
129// neighbouring cells. The returned grid must be deleted after use.
130// For ease of implementation, edge cells are double counted, to make them
131// have the same range as the non-edge cells.
133 auto* sumgrid = new IntGrid(gridsize(), bleft(), tright());
134 for (int y = 0; y < gridheight(); ++y) {
135 for (int x = 0; x < gridwidth(); ++x) {
136 int cell_count = 0;
137 for (int yoffset = -1; yoffset <= 1; ++yoffset) {
138 for (int xoffset = -1; xoffset <= 1; ++xoffset) {
139 int grid_x = x + xoffset;
140 int grid_y = y + yoffset;
141 ClipGridCoords(&grid_x, &grid_y);
142 cell_count += GridCellValue(grid_x, grid_y);
143 }
144 }
145 if (GridCellValue(x, y) > 1)
146 sumgrid->SetGridCell(x, y, cell_count);
147 }
148 }
149 return sumgrid;
150}
151
152// Returns true if more than half the area of the rect is covered by grid
153// cells that are over the threshold.
154bool IntGrid::RectMostlyOverThreshold(const TBOX& rect, int threshold) const {
155 int min_x, min_y, max_x, max_y;
156 GridCoords(rect.left(), rect.bottom(), &min_x, &min_y);
157 GridCoords(rect.right(), rect.top(), &max_x, &max_y);
158 int total_area = 0;
159 for (int y = min_y; y <= max_y; ++y) {
160 for (int x = min_x; x <= max_x; ++x) {
161 int value = GridCellValue(x, y);
162 if (value > threshold) {
163 TBOX cell_box(x * gridsize_, y * gridsize_,
164 (x + 1) * gridsize_, (y + 1) * gridsize_);
165 cell_box &= rect; // This is in-place box intersection.
166 total_area += cell_box.area();
167 }
168 }
169 }
170 return total_area * 2 > rect.area();
171}
172
173// Returns true if any cell value in the given rectangle is zero.
174bool IntGrid::AnyZeroInRect(const TBOX& rect) const {
175 int min_x, min_y, max_x, max_y;
176 GridCoords(rect.left(), rect.bottom(), &min_x, &min_y);
177 GridCoords(rect.right(), rect.top(), &max_x, &max_y);
178 for (int y = min_y; y <= max_y; ++y) {
179 for (int x = min_x; x <= max_x; ++x) {
180 if (GridCellValue(x, y) == 0)
181 return true;
182 }
183 }
184 return false;
185}
186
187// Returns a full-resolution binary pix in which each cell over the given
188// threshold is filled as a black square. pixDestroy after use.
189// Edge cells, which have a zero 4-neighbour, are not marked.
190Pix* IntGrid::ThresholdToPix(int threshold) const {
191 Pix* pix = pixCreate(tright().x() - bleft().x(),
192 tright().y() - bleft().y(), 1);
193 int cellsize = gridsize();
194 for (int y = 0; y < gridheight(); ++y) {
195 for (int x = 0; x < gridwidth(); ++x) {
196 if (GridCellValue(x, y) > threshold &&
197 GridCellValue(x - 1, y) > 0 && GridCellValue(x + 1, y) > 0 &&
198 GridCellValue(x, y - 1) > 0 && GridCellValue(x, y + 1) > 0) {
199 pixRasterop(pix, x * cellsize, tright().y() - ((y + 1) * cellsize),
200 cellsize, cellsize, PIX_SET, nullptr, 0, 0);
201 }
202 }
203 }
204 return pix;
205}
206
207// Make a Pix of the correct scaled size for the TraceOutline functions.
208static Pix* GridReducedPix(const TBOX& box, int gridsize,
209 ICOORD bleft, int* left, int* bottom) {
210 // Compute grid bounds of the outline and pad all round by 1.
211 int grid_left = (box.left() - bleft.x()) / gridsize - 1;
212 int grid_bottom = (box.bottom() - bleft.y()) / gridsize - 1;
213 int grid_right = (box.right() - bleft.x()) / gridsize + 1;
214 int grid_top = (box.top() - bleft.y()) / gridsize + 1;
215 *left = grid_left;
216 *bottom = grid_bottom;
217 return pixCreate(grid_right - grid_left + 1,
218 grid_top - grid_bottom + 1,
219 1);
220}
221
222// Helper function to return a scaled Pix with one pixel per grid cell,
223// set (black) where the given outline enters the corresponding grid cell,
224// and clear where the outline does not touch the grid cell.
225// Also returns the grid coords of the bottom-left of the Pix, in *left
226// and *bottom, which corresponds to (0, 0) on the Pix.
227// Note that the Pix is used upside-down, with (0, 0) being the bottom-left.
228Pix* TraceOutlineOnReducedPix(C_OUTLINE* outline, int gridsize,
229 ICOORD bleft, int* left, int* bottom) {
230 const TBOX& box = outline->bounding_box();
231 Pix* pix = GridReducedPix(box, gridsize, bleft, left, bottom);
232 int wpl = pixGetWpl(pix);
233 l_uint32* data = pixGetData(pix);
234 int length = outline->pathlength();
235 ICOORD pos = outline->start_pos();
236 for (int i = 0; i < length; ++i) {
237 int grid_x = (pos.x() - bleft.x()) / gridsize - *left;
238 int grid_y = (pos.y() - bleft.y()) / gridsize - *bottom;
239 SET_DATA_BIT(data + grid_y * wpl, grid_x);
240 pos += outline->step(i);
241 }
242 return pix;
243}
244#if 0 // Example code shows how to use TraceOutlineOnReducedPix.
245 C_OUTLINE_IT ol_it(blob->cblob()->out_list());
246 int grid_left, grid_bottom;
247 Pix* pix = TraceOutlineOnReducedPix(ol_it.data(), gridsize_, bleft_,
248 &grid_left, &grid_bottom);
249 grid->InsertPixPtBBox(grid_left, grid_bottom, pix, blob);
250 pixDestroy(&pix);
251#endif
252
253// As TraceOutlineOnReducedPix above, but on a BLOCK instead of a C_OUTLINE.
254Pix* TraceBlockOnReducedPix(BLOCK* block, int gridsize,
255 ICOORD bleft, int* left, int* bottom) {
256 const TBOX& box = block->pdblk.bounding_box();
257 Pix* pix = GridReducedPix(box, gridsize, bleft, left, bottom);
258 int wpl = pixGetWpl(pix);
259 l_uint32* data = pixGetData(pix);
260 ICOORDELT_IT it(block->pdblk.poly_block()->points());
261 for (it.mark_cycle_pt(); !it.cycled_list();) {
262 ICOORD pos = *it.data();
263 it.forward();
264 ICOORD next_pos = *it.data();
265 ICOORD line_vector = next_pos - pos;
266 int major, minor;
267 ICOORD major_step, minor_step;
268 line_vector.setup_render(&major_step, &minor_step, &major, &minor);
269 int accumulator = major / 2;
270 while (pos != next_pos) {
271 int grid_x = (pos.x() - bleft.x()) / gridsize - *left;
272 int grid_y = (pos.y() - bleft.y()) / gridsize - *bottom;
273 SET_DATA_BIT(data + grid_y * wpl, grid_x);
274 pos += major_step;
275 accumulator += minor;
276 if (accumulator >= major) {
277 accumulator -= major;
278 pos += minor_step;
279 }
280 }
281 }
282 return pix;
283}
284
285} // namespace tesseract.
#define ASSERT_HOST(x)
Definition: errcode.h:88
T ClipToRange(const T &x, const T &lower_bound, const T &upper_bound)
Definition: helpers.h:108
Pix * TraceBlockOnReducedPix(BLOCK *block, int gridsize, ICOORD bleft, int *left, int *bottom)
Definition: bbgrid.cpp:254
Pix * TraceOutlineOnReducedPix(C_OUTLINE *outline, int gridsize, ICOORD bleft, int *left, int *bottom)
Definition: bbgrid.cpp:228
ICOORD step(int index) const
Definition: coutln.h:144
const TBOX & bounding_box() const
Definition: coutln.h:113
const ICOORD & start_pos() const
Definition: coutln.h:148
int32_t pathlength() const
Definition: coutln.h:135
Definition: ocrblock.h:31
PDBLK pdblk
Page Description Block.
Definition: ocrblock.h:190
void bounding_box(ICOORD &bottom_left, ICOORD &top_right) const
get box
Definition: pdblock.h:59
POLY_BLOCK * poly_block() const
Definition: pdblock.h:55
integer coordinate
Definition: points.h:32
int16_t y() const
access_function
Definition: points.h:56
void setup_render(ICOORD *major_step, ICOORD *minor_step, int *major, int *minor) const
Definition: points.cpp:83
int16_t x() const
access function
Definition: points.h:52
Definition: points.h:189
void rotate(const FCOORD vec)
Definition: points.h:763
float y() const
Definition: points.h:210
float x() const
Definition: points.h:207
ICOORDELT_LIST * points()
Definition: polyblk.h:39
Definition: rect.h:34
const ICOORD & botleft() const
Definition: rect.h:92
void rotate(const FCOORD &vec)
Definition: rect.h:197
int16_t top() const
Definition: rect.h:58
int32_t area() const
Definition: rect.h:122
int16_t left() const
Definition: rect.h:72
int16_t bottom() const
Definition: rect.h:65
const ICOORD & topright() const
Definition: rect.h:104
int16_t right() const
Definition: rect.h:79
int gridsize() const
Definition: bbgrid.h:63
int gridheight() const
Definition: bbgrid.h:69
void ClipGridCoords(int *x, int *y) const
Definition: bbgrid.cpp:59
void Init(int gridsize, const ICOORD &bleft, const ICOORD &tright)
Definition: bbgrid.cpp:40
const ICOORD & bleft() const
Definition: bbgrid.h:72
int gridwidth() const
Definition: bbgrid.h:66
ICOORD tright_
Definition: bbgrid.h:91
void GridCoords(int x, int y, int *grid_x, int *grid_y) const
Definition: bbgrid.cpp:52
const ICOORD & tright() const
Definition: bbgrid.h:75
IntGrid * NeighbourhoodSum() const
Definition: bbgrid.cpp:132
Pix * ThresholdToPix(int threshold) const
Definition: bbgrid.cpp:190
int GridCellValue(int grid_x, int grid_y) const
Definition: bbgrid.h:120
void Init(int gridsize, const ICOORD &bleft, const ICOORD &tright)
Definition: bbgrid.cpp:79
bool RectMostlyOverThreshold(const TBOX &rect, int threshold) const
Definition: bbgrid.cpp:154
~IntGrid() override
Definition: bbgrid.cpp:73
void Rotate(const FCOORD &rotation)
Definition: bbgrid.cpp:99
bool AnyZeroInRect(const TBOX &rect) const
Definition: bbgrid.cpp:174