OL_BUCKETS Class Reference

#include <edgblob.h>

Public Member Functions
	~OL_BUCKETS ()=default
C_OUTLINE_LIST *	start_scan ()
C_OUTLINE_LIST *	scan_next ()
OL_BUCKETS::OL_BUCKETS
Construct an array of buckets for associating outlines into blobs.
	OL_BUCKETS (ICOORD bleft, ICOORD tright)
OL_BUCKETS::operator(
Return a pointer to a list of C_OUTLINEs corresponding to the given pixel coordinates.
C_OUTLINE_LIST *	operator() (int16_t x, int16_t y)
OL_BUCKETS::count_children
Find number of descendants of this outline.
int32_t	count_children (C_OUTLINE *outline, int32_t max_count)
OL_BUCKETS::outline_complexity
This is the new version of count_child. The goal of this function is to determine if an outline and its interiors could be part of a character blob. This is done by computing a "complexity" index for the outline, which is the return value of this function, and checking it against a threshold. The max_count is used for short-circuiting the recursion and forcing a rejection that guarantees to fail the threshold test. The complexity F for outline X with N children X[i] is F(X) = N + sum_i F(X[i]) * edges_children_per_grandchild so each layer of nesting increases complexity exponentially. An outline can be rejected as a text blob candidate if its complexity is too high, has too many children(likely a container), or has too many layers of nested inner loops. This has the side-effect of flattening out boxed or reversed video text regions.
int32_t	outline_complexity (C_OUTLINE *outline, int32_t max_count, int16_t depth)
OL_BUCKETS::extract_children
Find number of descendants of this outline.
void	extract_children (C_OUTLINE *outline, C_OUTLINE_IT *it)

Detailed Description

Definition at line 32 of file edgblob.h.

Constructor & Destructor Documentation

OL_BUCKETS::OL_BUCKETS	(	ICOORD	bleft,
		ICOORD	tright
	)

Definition at line 64 of file edgblob.cpp.

              :         bl(bleft), tr(tright) {
  bxdim =(tright.x() - bleft.x()) / BUCKETSIZE + 1;
  bydim =(tright.y() - bleft.y()) / BUCKETSIZE + 1;
                                 // make array
  buckets.reset(new C_OUTLINE_LIST[bxdim * bydim]);
  index = 0;
}

OL_BUCKETS::~OL_BUCKETS ( )

default

Member Function Documentation

int32_t OL_BUCKETS::count_children	(	C_OUTLINE *	outline,
		int32_t	max_count
	)

Definition at line 179 of file edgblob.cpp.

                                  {
  bool parent_box;              // could it be boxy
  int16_t xmin, xmax;           // coord limits
  int16_t ymin, ymax;
  int16_t xindex, yindex;       // current bucket
  C_OUTLINE *child;             // current child
  int32_t child_count;          // no of children
  int32_t grandchild_count;     // no of grandchildren
  int32_t parent_area;          // potential box
  float max_parent_area;        // potential box
  int32_t child_area;           // current child
  int32_t child_length;         // current child
  TBOX olbox;
  C_OUTLINE_IT child_it;        // search iterator

  olbox = outline->bounding_box();
  xmin =(olbox.left() - bl.x()) / BUCKETSIZE;
  xmax =(olbox.right() - bl.x()) / BUCKETSIZE;
  ymin =(olbox.bottom() - bl.y()) / BUCKETSIZE;
  ymax =(olbox.top() - bl.y()) / BUCKETSIZE;
  child_count = 0;
  grandchild_count = 0;
  parent_area = 0;
  max_parent_area = 0;
  parent_box = true;
  for (yindex = ymin; yindex <= ymax; yindex++) {
    for (xindex = xmin; xindex <= xmax; xindex++) {
      child_it.set_to_list(&buckets[yindex * bxdim + xindex]);
      if (child_it.empty())
        continue;
      for (child_it.mark_cycle_pt(); !child_it.cycled_list();
           child_it.forward()) {
        child = child_it.data();
        if (child != outline && *child < *outline) {
          child_count++;
          if (child_count <= max_count) {
            int max_grand =(max_count - child_count) /
                            edges_children_per_grandchild;
            if (max_grand > 0)
              grandchild_count += count_children(child, max_grand) *
                                  edges_children_per_grandchild;
            else
              grandchild_count += count_children(child, 1);
          }
          if (child_count + grandchild_count > max_count) {
            if (edges_debug)
              tprintf("Discarding parent with child count=%d, gc=%d\n",
                      child_count,grandchild_count);
            return child_count + grandchild_count;
          }
          if (parent_area == 0) {
            parent_area = outline->outer_area();
            if (parent_area < 0)
              parent_area = -parent_area;
            max_parent_area = outline->bounding_box().area() * edges_boxarea;
            if (parent_area < max_parent_area)
              parent_box = false;
          }
          if (parent_box &&
              (!edges_children_fix ||
               child->bounding_box().height() > edges_min_nonhole)) {
            child_area = child->outer_area();
            if (child_area < 0)
              child_area = -child_area;
            if (edges_children_fix) {
              if (parent_area - child_area < max_parent_area) {
                parent_box = false;
                continue;
              }
              if (grandchild_count > 0) {
                if (edges_debug)
                  tprintf("Discarding parent of area %d, child area=%d, max%g "
                          "with gc=%d\n",
                          parent_area, child_area, max_parent_area,
                          grandchild_count);
                return max_count + 1;
              }
              child_length = child->pathlength();
              if (child_length * child_length >
                  child_area * edges_patharea_ratio) {
                if (edges_debug)
                  tprintf("Discarding parent of area %d, child area=%d, max%g "
                          "with child length=%d\n",
                          parent_area, child_area, max_parent_area,
                          child_length);
                return max_count + 1;
              }
            }
            if (child_area < child->bounding_box().area() * edges_childarea) {
              if (edges_debug)
                tprintf("Discarding parent of area %d, child area=%d, max%g "
                        "with child rect=%d\n",
                        parent_area, child_area, max_parent_area,
                        child->bounding_box().area());
              return max_count + 1;
            }
          }
        }
      }
    }
  }
  return child_count + grandchild_count;
}

void OL_BUCKETS::extract_children	(	C_OUTLINE *	outline,
		C_OUTLINE_IT *	it
	)

Definition at line 295 of file edgblob.cpp.

                                   {
  int16_t xmin, xmax;              // coord limits
  int16_t ymin, ymax;
  int16_t xindex, yindex;          // current bucket
  TBOX olbox;
  C_OUTLINE_IT child_it;         // search iterator

  olbox = outline->bounding_box();
  xmin =(olbox.left() - bl.x()) / BUCKETSIZE;
  xmax =(olbox.right() - bl.x()) / BUCKETSIZE;
  ymin =(olbox.bottom() - bl.y()) / BUCKETSIZE;
  ymax =(olbox.top() - bl.y()) / BUCKETSIZE;
  for (yindex = ymin; yindex <= ymax; yindex++) {
    for (xindex = xmin; xindex <= xmax; xindex++) {
      child_it.set_to_list(&buckets[yindex * bxdim + xindex]);
      for (child_it.mark_cycle_pt(); !child_it.cycled_list();
           child_it.forward()) {
        if (*child_it.data() < *outline) {
          it->add_after_then_move(child_it.extract());
        }
      }
    }
  }
}

C_OUTLINE_LIST * OL_BUCKETS::operator()	(	int16_t	x,
		int16_t	y
	)

Definition at line 83 of file edgblob.cpp.

           {
  return &buckets[(y-bl.y()) / BUCKETSIZE * bxdim + (x-bl.x()) / BUCKETSIZE];
}

int32_t OL_BUCKETS::outline_complexity	(	C_OUTLINE *	outline,
		int32_t	max_count,
		int16_t	depth
	)

Definition at line 110 of file edgblob.cpp.

                                      {
  int16_t xmin, xmax;              // coord limits
  int16_t ymin, ymax;
  int16_t xindex, yindex;          // current bucket
  C_OUTLINE *child;              // current child
  int32_t child_count;             // no of children
  int32_t grandchild_count;        // no of grandchildren
  C_OUTLINE_IT child_it;         // search iterator

  TBOX olbox = outline->bounding_box();
  xmin =(olbox.left() - bl.x()) / BUCKETSIZE;
  xmax =(olbox.right() - bl.x()) / BUCKETSIZE;
  ymin =(olbox.bottom() - bl.y()) / BUCKETSIZE;
  ymax =(olbox.top() - bl.y()) / BUCKETSIZE;
  child_count = 0;
  grandchild_count = 0;
  if (++depth > edges_max_children_layers)  // nested loops are too deep
    return max_count + depth;

  for (yindex = ymin; yindex <= ymax; yindex++) {
    for (xindex = xmin; xindex <= xmax; xindex++) {
      child_it.set_to_list(&buckets[yindex * bxdim + xindex]);
      if (child_it.empty())
        continue;
      for (child_it.mark_cycle_pt(); !child_it.cycled_list();
           child_it.forward()) {
        child = child_it.data();
        if (child == outline || !(*child < *outline))
          continue;
        child_count++;

        if (child_count > edges_max_children_per_outline) {   // too fragmented
          if (edges_debug)
            tprintf("Discard outline on child_count=%d > "
                    "max_children_per_outline=%d\n",
                    child_count,
                    static_cast<int32_t>(edges_max_children_per_outline));
          return max_count + child_count;
        }

        // Compute the "complexity" of each child recursively
        int32_t remaining_count = max_count - child_count - grandchild_count;
        if (remaining_count > 0)
          grandchild_count += edges_children_per_grandchild *
                              outline_complexity(child, remaining_count, depth);
        if (child_count + grandchild_count > max_count) {  // too complex
          if (edges_debug)
            tprintf("Disgard outline on child_count=%d + grandchild_count=%d "
                    "> max_count=%d\n",
                    child_count, grandchild_count, max_count);
          return child_count + grandchild_count;
        }
      }
    }
  }
  return child_count + grandchild_count;
}

C_OUTLINE_LIST* OL_BUCKETS::scan_next ( )

inline

Definition at line 51 of file edgblob.h.

                                {
      for (; buckets[index].empty () && index < bxdim * bydim - 1; index++);
      return &buckets[index];
    }

C_OUTLINE_LIST* OL_BUCKETS::start_scan ( )

inline

Definition at line 45 of file edgblob.h.

                                 {
      for (index = 0; buckets[index].empty () && index < bxdim * bydim - 1;
        index++);
      return &buckets[index];
    }

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The documentation for this class was generated from the following files:

• src/textord/edgblob.h
• src/textord/edgblob.cpp