Moved params from global in page layout to tesseractclass, improved single column layout analysis

ccmain/pagesegmain.cpp

@@ -340,6 +340,7 @@ ColumnFinder* Tesseract::SetupPageSegAndDetectOrientation(
     finder = new ColumnFinder(static_cast<int>(to_block->line_size),
                               blkbox.botleft(), blkbox.topright(),
                               source_resolution_, textord_use_cjk_fp_model,
+                              textord_tabfind_aligned_gap_fraction,
                               &v_lines, &h_lines, vertical_x, vertical_y);
 
     finder->SetupAndFilterNoise(*photo_mask_pix, to_block);
@@ -354,7 +355,12 @@ ColumnFinder* Tesseract::SetupPageSegAndDetectOrientation(
     // We want the text lines horizontal, (vertical text indicates vertical
     // textlines) which may conflict (eg vertically written CJK).
     int osd_orientation = 0;
-    bool vertical_text = finder->IsVerticallyAlignedText(to_block, &osd_blobs);
+    bool vertical_text = textord_tabfind_force_vertical_text;
+    if (!vertical_text && textord_tabfind_vertical_text) {
+      vertical_text =
+          finder->IsVerticallyAlignedText(textord_tabfind_vertical_text_ratio,
+                                          to_block, &osd_blobs);
+    }
     if (osd && osd_tess != NULL && osr != NULL) {
       GenericVector<int> osd_scripts;
       if (osd_tess != this) {

ccmain/tesseractclass.cpp

@@ -419,6 +419,16 @@ Tesseract::Tesseract()
                      "for layout analysis.", this->params()),
     BOOL_MEMBER(textord_equation_detect, false, "Turn on equation detector",
                 this->params()),
+    BOOL_MEMBER(textord_tabfind_vertical_text, true,
+                "Enable vertical detection", this->params()),
+    BOOL_MEMBER(textord_tabfind_force_vertical_text, false,
+                "Force using vertical text page mode", this->params()),
+    double_MEMBER(textord_tabfind_vertical_text_ratio, 0.5,
+                  "Fraction of textlines deemed vertical to use vertical page "
+                  "mode", this->params()),
+    double_MEMBER(textord_tabfind_aligned_gap_fraction, 0.75,
+                  "Fraction of height used as a minimum gap for aligned blobs.",
+                  this->params()),
     INT_MEMBER(tessedit_parallelize, 0, "Run in parallel where possible",
                 this->params()),
 
@@ -430,6 +440,9 @@ Tesseract::Tesseract()
     // reasonably sure that Tesseract users have updated their data files.
     //
     // BEGIN DEPRECATED PARAMETERS
+    BOOL_MEMBER(textord_tabfind_vertical_horizontal_mix, true,
+                "find horizontal lines such as headers in vertical page mode",
+                this->params()),
     INT_MEMBER(tessedit_ok_mode, 5,
                "Acceptance decision algorithm", this->params()),
     BOOL_INIT_MEMBER(load_fixed_length_dawgs, true, "Load fixed length dawgs"

ccmain/tesseractclass.h

@@ -1000,6 +1000,14 @@ class Tesseract : public Wordrec {
              "Only initialize with the config file. Useful if the instance is "
              "not going to be used for OCR but say only for layout analysis.");
   BOOL_VAR_H(textord_equation_detect, false, "Turn on equation detector");
+  BOOL_VAR_H(textord_tabfind_vertical_text, true, "Enable vertical detection");
+  BOOL_VAR_H(textord_tabfind_force_vertical_text, false,
+             "Force using vertical text page mode");
+  double_VAR_H(textord_tabfind_vertical_text_ratio, 0.5,
+               "Fraction of textlines deemed vertical to use vertical page "
+               "mode");
+  double_VAR_H(textord_tabfind_aligned_gap_fraction, 0.75,
+               "Fraction of height used as a minimum gap for aligned blobs.");
   INT_VAR_H(tessedit_parallelize, 0, "Run in parallel where possible");
 
   // The following parameters were deprecated and removed from their original
@@ -1010,6 +1018,8 @@ class Tesseract : public Wordrec {
   // reasonably sure that Tesseract users have updated their data files.
   //
   // BEGIN DEPRECATED PARAMETERS
+  BOOL_VAR_H(textord_tabfind_vertical_horizontal_mix, true,
+             "find horizontal lines such as headers in vertical page mode");
   INT_VAR_H(tessedit_ok_mode, 5, "Acceptance decision algorithm");
   BOOL_VAR_H(load_fixed_length_dawgs, true,  "Load fixed length"
              " dawgs (e.g. for non-space delimited languages)");

textord/colfind.cpp

@@ -84,6 +84,7 @@ ScrollView* ColumnFinder::blocks_win_ = NULL;
 ColumnFinder::ColumnFinder(int gridsize,
                            const ICOORD& bleft, const ICOORD& tright,
                            int resolution, bool cjk_script,
+                           double aligned_gap_fraction,
                            TabVector_LIST* vlines, TabVector_LIST* hlines,
                            int vertical_x, int vertical_y)
   : TabFind(gridsize, bleft, tright, vlines, vertical_x, vertical_y,
@@ -91,6 +92,7 @@ ColumnFinder::ColumnFinder(int gridsize,
     cjk_script_(cjk_script),
     min_gutter_width_(static_cast<int>(kMinGutterWidthGrid * gridsize)),
     mean_column_gap_(tright.x() - bleft.x()),
+    tabfind_aligned_gap_fraction_(aligned_gap_fraction),
     reskew_(1.0f, 0.0f), rotation_(1.0f, 0.0f), rerotate_(1.0f, 0.0f),
     best_columns_(NULL), stroke_width_(NULL),
     part_grid_(gridsize, bleft, tright), nontext_map_(NULL),
@@ -184,9 +186,11 @@ void ColumnFinder::SetupAndFilterNoise(Pix* photo_mask_pix,
 // is vertical, like say Japanese, or due to text whose writing direction is
 // horizontal but whose text appears vertically aligned because the image is
 // not the right way up.
-bool ColumnFinder::IsVerticallyAlignedText(TO_BLOCK* block,
+bool ColumnFinder::IsVerticallyAlignedText(double find_vertical_text_ratio,
+                                           TO_BLOCK* block,
                                            BLOBNBOX_CLIST* osd_blobs) {
-  return stroke_width_->TestVerticalTextDirection(block, osd_blobs);
+  return stroke_width_->TestVerticalTextDirection(find_vertical_text_ratio,
+                                                  block, osd_blobs);
 }
 
 // Rotates the blobs and the TabVectors so that the gross writing direction
@@ -292,7 +296,8 @@ int ColumnFinder::FindBlocks(PageSegMode pageseg_mode,
   pixOr(photo_mask_pix, photo_mask_pix, nontext_map_);
   stroke_width_->FindLeaderPartitions(input_block, &part_grid_);
   stroke_width_->RemoveLineResidue(&big_parts_);
-  FindInitialTabVectors(NULL, min_gutter_width_, input_block);
+  FindInitialTabVectors(NULL, min_gutter_width_, tabfind_aligned_gap_fraction_,
+                        input_block);
   SetBlockRuleEdges(input_block);
   stroke_width_->GradeBlobsIntoPartitions(rerotate_, input_block, nontext_map_,
                                           denorm_, cjk_script_, &projection_,
@@ -353,7 +358,8 @@ int ColumnFinder::FindBlocks(PageSegMode pageseg_mode,
       // Find the tab stops, estimate skew, and deskew the tabs, blobs and
       // part_grid_.
       FindTabVectors(&horizontal_lines_, &image_bblobs_, input_block,
-                     min_gutter_width_, &part_grid_, &deskew_, &reskew_);
+                     min_gutter_width_, tabfind_aligned_gap_fraction_,
+                     &part_grid_, &deskew_, &reskew_);
       // Add the deskew to the denorm_.
       DENORM* new_denorm = new DENORM;
       new_denorm->SetupNormalization(NULL, &deskew_, denorm_,
@@ -596,11 +602,11 @@ bool ColumnFinder::MakeColumns(bool single_column) {
   bool has_columns = !column_sets_.empty();
   if (has_columns) {
     // Divide the page into sections of uniform column layout.
-    AssignColumns(part_sets);
+    bool any_multi_column = AssignColumns(part_sets);
     if (textord_tabfind_show_columns) {
       DisplayColumnBounds(&part_sets);
     }
-    ComputeMeanColumnGap();
+    ComputeMeanColumnGap(any_multi_column);
   }
   for (int i = 0; i < part_sets.size(); ++i) {
     ColPartitionSet* line_set = part_sets.get(i);
@@ -663,7 +669,8 @@ void ColumnFinder::PrintColumnCandidates(const char* title) {
 // tweak of extending the modal region over small breaks in compatibility.
 // Where modal regions overlap, the boundary is chosen so as to minimize
 // the cost in terms of ColPartitions not fitting an approved column.
-void ColumnFinder::AssignColumns(const PartSetVector& part_sets) {
+// Returns true if any part of the page is multi-column.
+bool ColumnFinder::AssignColumns(const PartSetVector& part_sets) {
   int set_count = part_sets.size();
   ASSERT_HOST(set_count == gridheight());
   // Allocate and init the best_columns_.
@@ -708,6 +715,7 @@ void ColumnFinder::AssignColumns(const PartSetVector& part_sets) {
       }
     }
   }
+  bool any_multi_column = false;
   // Assign a column set to each vertical grid position.
   // While there is an unassigned range, find its mode.
   int start, end;
@@ -745,6 +753,8 @@ void ColumnFinder::AssignColumns(const PartSetVector& part_sets) {
     // Assign the column to the range, which now may overlap with other ranges.
     AssignColumnToRange(column_set_id, start, end, column_set_costs,
                         assigned_costs);
+    if (column_sets_.get(column_set_id)->GoodColumnCount() > 1)
+      any_multi_column = true;
   }
   // If anything remains unassigned, the whole lot is unassigned, so
   // arbitrarily assign id 0.
@@ -758,6 +768,7 @@ void ColumnFinder::AssignColumns(const PartSetVector& part_sets) {
   delete [] assigned_costs;
   delete [] any_columns_possible;
   delete [] column_set_costs;
+  return any_multi_column;
 }
 
 // Finds the biggest range in part_sets_ that has no assigned column, but
@@ -915,7 +926,7 @@ void ColumnFinder::AssignColumnToRange(int column_set_id, int start, int end,
 }
 
 // Computes the mean_column_gap_.
-void ColumnFinder::ComputeMeanColumnGap() {
+void ColumnFinder::ComputeMeanColumnGap(bool any_multi_column) {
   int total_gap = 0;
   int total_width = 0;
   int gap_samples = 0;
@@ -927,8 +938,8 @@ void ColumnFinder::ComputeMeanColumnGap() {
                                                     &total_gap,
                                                     &gap_samples);
   }
-  mean_column_gap_ = gap_samples > 0 ? total_gap / gap_samples
+  mean_column_gap_ = any_multi_column && gap_samples > 0
-                                     : total_width / width_samples;
+      ? total_gap / gap_samples : total_width / width_samples;
 }
 
 //////// Functions that manipulate ColPartitions in the part_grid_ /////

textord/colfind.h

@@ -61,8 +61,9 @@ class ColumnFinder : public TabFind {
   // layout analysis to assist in detecting horizontal vs vertically written
   // textlines.
   ColumnFinder(int gridsize, const ICOORD& bleft, const ICOORD& tright,
-               int resolution, bool cjk_script, TabVector_LIST* vlines,
+               int resolution, bool cjk_script, double aligned_gap_fraction,
-               TabVector_LIST* hlines, int vertical_x, int vertical_y);
+               TabVector_LIST* vlines, TabVector_LIST* hlines,
+               int vertical_x, int vertical_y);
   virtual ~ColumnFinder();
 
   // Accessors for testing
@@ -118,7 +119,9 @@ class ColumnFinder : public TabFind {
   // is vertical, like say Japanese, or due to text whose writing direction is
   // horizontal but whose text appears vertically aligned because the image is
   // not the right way up.
-  bool IsVerticallyAlignedText(TO_BLOCK* block, BLOBNBOX_CLIST* osd_blobs);
+  // find_vertical_text_ratio should be textord_tabfind_vertical_text_ratio.
+  bool IsVerticallyAlignedText(double find_vertical_text_ratio,
+                               TO_BLOCK* block, BLOBNBOX_CLIST* osd_blobs);
 
   // Rotates the blobs and the TabVectors so that the gross writing direction
   // (text lines) are horizontal and lines are read down the page.
@@ -188,7 +191,8 @@ class ColumnFinder : public TabFind {
   void PrintColumnCandidates(const char* title);
   // Finds the optimal set of columns that cover the entire image with as
   // few changes in column partition as possible.
-  void AssignColumns(const PartSetVector& part_sets);
+  // Returns true if any part of the page is multi-column.
+  bool AssignColumns(const PartSetVector& part_sets);
   // Finds the biggest range in part_sets_ that has no assigned column, but
   // column assignment is possible.
   bool BiggestUnassignedRange(int set_count, const bool* any_columns_possible,
@@ -218,7 +222,7 @@ class ColumnFinder : public TabFind {
                            int** column_set_costs, int* assigned_costs);
 
   // Computes the mean_column_gap_.
-  void ComputeMeanColumnGap();
+  void ComputeMeanColumnGap(bool any_multi_column);
 
   //////// Functions that manipulate ColPartitions in the part_grid_ /////
   //////// to split, merge, find margins, and find types.  //////////////
@@ -299,6 +303,9 @@ class ColumnFinder : public TabFind {
   int min_gutter_width_;
   // The mean gap between columns over the page.
   int mean_column_gap_;
+  // Config param saved at construction time. Modifies min_gutter_width_ with
+  // vertical text to prevent detection of vertical text as columns.
+  double tabfind_aligned_gap_fraction_;
   // The rotation vector needed to convert original coords to deskewed.
   FCOORD deskew_;
   // The rotation vector needed to convert deskewed back to original coords.

textord/colpartitiongrid.cpp

@@ -1080,7 +1080,7 @@ void ColPartitionGrid::FindFigureCaptions() {
         for (partner_it.mark_cycle_pt(); !partner_it.cycled_list();
              partner_it.forward()) {
           ColPartition* partner = partner_it.data();
-          if (!partner->IsTextType()) continue;
+          if (!partner->IsTextType() || partner->type() == PT_TABLE) continue;
           const TBOX& partner_box = partner->bounding_box();
           if (debug) {
             tprintf("Finding figure captions for image part:");

textord/colpartitionset.cpp

@@ -49,6 +49,17 @@ ColPartitionSet::ColPartitionSet(ColPartition* part) {
 ColPartitionSet::~ColPartitionSet() {
 }
 
+// Returns the number of columns of good width.
+int ColPartitionSet::GoodColumnCount() const {
+  int num_good_cols = 0;
+  // This is a read-only iteration of the list.
+  ColPartition_IT it(const_cast<ColPartition_LIST*>(&parts_));
+  for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
+    if (it.data()->good_width()) ++num_good_cols;
+  }
+  return num_good_cols;
+}
+
 // Return an element of the parts_ list from its index.
 ColPartition* ColPartitionSet::GetColumnByIndex(int index) {
   ColPartition_IT it(&parts_);

textord/colpartitionset.h

@@ -50,13 +50,16 @@ class ColPartitionSet : public ELIST_LINK {
   const TBOX& bounding_box() const {
     return bounding_box_;
   }
-  bool Empty() {
+  bool Empty() const {
     return parts_.empty();
   }
-  int ColumnCount() {
+  int ColumnCount() const {
     return parts_.length();
   }
 
+  // Returns the number of columns of good width.
+  int GoodColumnCount() const;
+
   // Return an element of the parts_ list from its index.
   ColPartition* GetColumnByIndex(int index);
 

textord/strokewidth.cpp

@@ -43,13 +43,6 @@ namespace tesseract {
 
 INT_VAR(textord_tabfind_show_strokewidths, 0, "Show stroke widths");
 BOOL_VAR(textord_tabfind_only_strokewidths, false, "Only run stroke widths");
-BOOL_VAR(textord_tabfind_vertical_text, true, "Enable vertical detection");
-BOOL_VAR(textord_tabfind_force_vertical_text, false,
-         "Force using vertical text page mode");
-BOOL_VAR(textord_tabfind_vertical_horizontal_mix, true,
-         "find horizontal lines such as headers in vertical page mode");
-double_VAR(textord_tabfind_vertical_text_ratio, 0.5,
-           "Fraction of textlines deemed vertical to use vertical page mode");
 
 /** Allowed proportional change in stroke width to be the same font. */
 const double kStrokeWidthFractionTolerance = 0.125;
@@ -215,11 +208,9 @@ static void CollectHorizVertBlobs(BLOBNBOX_LIST* input_blobs,
 // after rotating everything, otherwise the work done here will be enough.
 // If osd_blobs is not null, a list of blobs from the dominant textline
 // direction are returned for use in orientation and script detection.
-bool StrokeWidth::TestVerticalTextDirection(TO_BLOCK* block,
+bool StrokeWidth::TestVerticalTextDirection(double find_vertical_text_ratio,
+                                            TO_BLOCK* block,
                                             BLOBNBOX_CLIST* osd_blobs) {
-  if (textord_tabfind_force_vertical_text) return true;
-  if (!textord_tabfind_vertical_text) return false;
-
   int vertical_boxes = 0;
   int horizontal_boxes = 0;
   // Count vertical normal and large blobs.
@@ -242,7 +233,7 @@ bool StrokeWidth::TestVerticalTextDirection(TO_BLOCK* block,
     return false;
   }
   int min_vert_boxes = static_cast<int>((vertical_boxes + horizontal_boxes) *
-                                        textord_tabfind_vertical_text_ratio);
+                                        find_vertical_text_ratio);
   if (vertical_boxes >= min_vert_boxes) {
     if (osd_blobs != NULL) {
       BLOBNBOX_C_IT osd_it(osd_blobs);

textord/strokewidth.h

@@ -78,7 +78,9 @@ class StrokeWidth : public BlobGrid {
   // after rotating everything, otherwise the work done here will be enough.
   // If osd_blobs is not null, a list of blobs from the dominant textline
   // direction are returned for use in orientation and script detection.
-  bool TestVerticalTextDirection(TO_BLOCK* block,
+  // find_vertical_text_ratio should be textord_tabfind_vertical_text_ratio.
+  bool TestVerticalTextDirection(double find_vertical_text_ratio,
+                                 TO_BLOCK* block,
                                  BLOBNBOX_CLIST* osd_blobs);
 
   // Corrects the data structures for the given rotation.

textord/tabfind.cpp

@@ -82,8 +82,6 @@ const double kCosMaxSkewAngle = 0.866025;
 
 BOOL_VAR(textord_tabfind_show_initialtabs, false, "Show tab candidates");
 BOOL_VAR(textord_tabfind_show_finaltabs, false, "Show tab vectors");
-double_VAR(textord_tabfind_aligned_gap_fraction, 0.75,
-           "Fraction of height used as a minimum gap for aligned blobs.");
 
 TabFind::TabFind(int gridsize, const ICOORD& bleft, const ICOORD& tright,
                  TabVector_LIST* vlines, int vertical_x, int vertical_y,
@@ -420,7 +418,7 @@ bool TabFind::CommonWidth(int width) {
   ICOORDELT_IT it(&column_widths_);
   for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
     ICOORDELT* w = it.data();
-    if (NearlyEqual<int>(width, w->x(), 1))
+    if (w->x() - 1 <= width && width <= w->y() + 1)
       return true;
   }
   return false;
@@ -446,9 +444,11 @@ bool TabFind::VeryDifferentSizes(int size1, int size2) {
 bool TabFind::FindTabVectors(TabVector_LIST* hlines,
                              BLOBNBOX_LIST* image_blobs, TO_BLOCK* block,
                              int min_gutter_width,
+                             double tabfind_aligned_gap_fraction,
                              ColPartitionGrid* part_grid,
                              FCOORD* deskew, FCOORD* reskew) {
   ScrollView* tab_win = FindInitialTabVectors(image_blobs, min_gutter_width,
+                                              tabfind_aligned_gap_fraction,
                                               block);
   ComputeColumnWidths(tab_win, part_grid);
   TabVector::MergeSimilarTabVectors(vertical_skew_, &vectors_, this);
@@ -540,6 +540,7 @@ ScrollView* TabFind::DisplayTabVectors(ScrollView* tab_win) {
 // is mostly of vertical alignment.
 ScrollView* TabFind::FindInitialTabVectors(BLOBNBOX_LIST* image_blobs,
                                            int min_gutter_width,
+                                           double tabfind_aligned_gap_fraction,
                                            TO_BLOCK* block) {
   if (textord_tabfind_show_initialtabs) {
     ScrollView* line_win = MakeWindow(0, 0, "VerticalLines");
@@ -549,7 +550,8 @@ ScrollView* TabFind::FindInitialTabVectors(BLOBNBOX_LIST* image_blobs,
   if (image_blobs != NULL)
     InsertBlobsToGrid(true, false, image_blobs, this);
   InsertBlobsToGrid(true, false, &block->blobs, this);
-  ScrollView* initial_win = FindTabBoxes(min_gutter_width);
+  ScrollView* initial_win = FindTabBoxes(min_gutter_width,
+                                         tabfind_aligned_gap_fraction);
   FindAllTabVectors(min_gutter_width);
 
   TabVector::MergeSimilarTabVectors(vertical_skew_, &vectors_, this);
@@ -581,7 +583,8 @@ static void DisplayBoxVector(const GenericVector<BLOBNBOX*>& boxes,
 
 // For each box in the grid, decide whether it is a candidate tab-stop,
 // and if so add it to the left/right tab boxes.
-ScrollView* TabFind::FindTabBoxes(int min_gutter_width) {
+ScrollView* TabFind::FindTabBoxes(int min_gutter_width,
+                                  double tabfind_aligned_gap_fraction) {
   left_tab_boxes_.clear();
   right_tab_boxes_.clear();
   // For every bbox in the grid, determine whether it uses a tab on an edge.
@@ -589,7 +592,7 @@ ScrollView* TabFind::FindTabBoxes(int min_gutter_width) {
   gsearch.StartFullSearch();
   BLOBNBOX* bbox;
   while ((bbox = gsearch.NextFullSearch()) != NULL) {
-    if (TestBoxForTabs(bbox, min_gutter_width)) {
+    if (TestBoxForTabs(bbox, min_gutter_width, tabfind_aligned_gap_fraction)) {
       // If it is any kind of tab, insert it into the vectors.
       if (bbox->left_tab_type() != TT_NONE)
         left_tab_boxes_.push_back(bbox);
@@ -616,7 +619,8 @@ ScrollView* TabFind::FindTabBoxes(int min_gutter_width) {
   return tab_win;
 }
 
-bool TabFind::TestBoxForTabs(BLOBNBOX* bbox, int min_gutter_width) {
+bool TabFind::TestBoxForTabs(BLOBNBOX* bbox, int min_gutter_width,
+                             double tabfind_aligned_gap_fraction) {
   GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> radsearch(this);
   TBOX box = bbox->bounding_box();
   // If there are separator lines, get the column edges.
@@ -642,7 +646,7 @@ bool TabFind::TestBoxForTabs(BLOBNBOX* bbox, int min_gutter_width) {
   // increased under the assumption that column partition is always larger
   // than line spacing.
   int min_spacing =
-      static_cast<int>(height * textord_tabfind_aligned_gap_fraction);
+      static_cast<int>(height * tabfind_aligned_gap_fraction);
   if (min_gutter_width > min_spacing)
     min_spacing = min_gutter_width;
   int min_ragged_gutter = kRaggedGutterMultiple * gridsize();
@@ -989,9 +993,16 @@ void TabFind::ComputeColumnWidths(ScrollView* tab_win,
     col_widths.print();
   // Now make a list of column widths.
   MakeColumnWidths(col_widths_size, &col_widths);
+  // Turn the column width into a range.
+  ApplyPartitionsToColumnWidths(part_grid, NULL);
 }
 
-// Find column width and pair-up tab vectors with existing ColPartitions.
+// Finds column width and:
+//   if col_widths is not null (pass1):
+//     pair-up tab vectors with existing ColPartitions and accumulate widths.
+//   else (pass2):
+//     find the largest real partition width for each recorded column width,
+//     to be used as the minimum acceptable width.
 void TabFind::ApplyPartitionsToColumnWidths(ColPartitionGrid* part_grid,
                                             STATS* col_widths) {
   // For every ColPartition in the part_grid, add partners to the tabvectors
@@ -1015,13 +1026,27 @@ void TabFind::ApplyPartitionsToColumnWidths(ColPartitionGrid* part_grid,
     if (right_vector == NULL || right_vector->IsLeftTab())
       continue;
 
-    AddPartnerVector(left_blob, right_blob, left_vector, right_vector);
     int line_left = left_vector->XAtY(left_blob->bounding_box().bottom());
     int line_right = right_vector->XAtY(right_blob->bounding_box().bottom());
     // Add to STATS of measurements if the width is significant.
     int width = line_right - line_left;
+    if (col_widths != NULL) {
+      AddPartnerVector(left_blob, right_blob, left_vector, right_vector);
       if (width >= kMinColumnWidth)
         col_widths->add(width / kColumnWidthFactor, 1);
+    } else {
+      width /= kColumnWidthFactor;
+      ICOORDELT_IT it(&column_widths_);
+      for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
+        ICOORDELT* w = it.data();
+        if (NearlyEqual<int>(width, w->y(), 1)) {
+          int true_width = part->bounding_box().width() / kColumnWidthFactor;
+          if (true_width <= w->y() && true_width > w->x())
+            w->set_x(true_width);
+          break;
+        }
+      }
+    }
   }
 }
 
@@ -1052,7 +1077,7 @@ void TabFind::MakeColumnWidths(int col_widths_size, STATS* col_widths) {
     }
     if (col_count > kMinLinesInColumn &&
         col_count > kMinFractionalLinesInColumn * total_col_count) {
-      ICOORDELT* w = new ICOORDELT(width, col_count);
+      ICOORDELT* w = new ICOORDELT(0, width);
       w_it.add_after_then_move(w);
       if (textord_debug_tabfind)
         tprintf("Column of width %d has %d = %.2f%% lines\n",

textord/tabfind.h

@@ -25,15 +25,6 @@
 #include "tabvector.h"
 #include "linefind.h"
 
-extern BOOL_VAR_H(textord_tabfind_force_vertical_text, false,
-       "Force using vertical text page mode");
-extern BOOL_VAR_H(textord_tabfind_vertical_horizontal_mix, true,
-       "find horizontal lines such as headers in vertical page mode");
-extern double_VAR_H(textord_tabfind_vertical_text_ratio, 0.5,
-       "Fraction of textlines deemed vertical to use vertical page mode");
-extern double_VAR_H(textord_tabfind_aligned_gap_fraction, 0.75,
-       "Fraction of height used as a minimum gap for aligned blobs.");
-
 class BLOBNBOX;
 class BLOBNBOX_LIST;
 class TO_BLOCK;
@@ -190,10 +181,12 @@ class TabFind : public AlignedBlob {
    * Top-level function to find TabVectors in an input page block.
    * Returns false if the detected skew angle is impossible.
    * Applies the detected skew angle to deskew the tabs, blobs and part_grid.
+   * tabfind_aligned_gap_fraction should be the value of parameter
+   * textord_tabfind_aligned_gap_fraction
    */
   bool FindTabVectors(TabVector_LIST* hlines,
                       BLOBNBOX_LIST* image_blobs, TO_BLOCK* block,
-                      int min_gutter_width,
+                      int min_gutter_width, double tabfind_aligned_gap_fraction,
                       ColPartitionGrid* part_grid,
                       FCOORD* deskew, FCOORD* reskew);
 
@@ -220,8 +213,12 @@ class TabFind : public AlignedBlob {
   // true, this finds vertical textlines in possibly rotated blob space.
   // In other words, when the page has mostly vertical lines and is rotated,
   // setting this to true will find horizontal lines on the page.
+  // tabfind_aligned_gap_fraction should be the value of parameter
+  // textord_tabfind_aligned_gap_fraction
   ScrollView* FindInitialTabVectors(BLOBNBOX_LIST* image_blobs,
-                                    int min_gutter_width, TO_BLOCK* block);
+                                    int min_gutter_width,
+                                    double tabfind_aligned_gap_fraction,
+                                    TO_BLOCK* block);
 
   // Apply the given rotation to the given list of blobs.
   static void RotateBlobList(const FCOORD& rotation, BLOBNBOX_LIST* blobs);
@@ -245,11 +242,17 @@ class TabFind : public AlignedBlob {
  private:
   // For each box in the grid, decide whether it is a candidate tab-stop,
   // and if so add it to the left and right tab boxes.
-  ScrollView* FindTabBoxes(int min_gutter_width);
+  // tabfind_aligned_gap_fraction should be the value of parameter
+  // textord_tabfind_aligned_gap_fraction
+  ScrollView* FindTabBoxes(int min_gutter_width,
+                           double tabfind_aligned_gap_fraction);
 
   // Return true if this box looks like a candidate tab stop, and set
   // the appropriate tab type(s) to TT_UNCONFIRMED.
-  bool TestBoxForTabs(BLOBNBOX* bbox, int min_gutter_width);
+  // tabfind_aligned_gap_fraction should be the value of parameter
+  // textord_tabfind_aligned_gap_fraction
+  bool TestBoxForTabs(BLOBNBOX* bbox, int min_gutter_width,
+                      double tabfind_aligned_gap_fraction);
 
   // Returns true if there is nothing in the rectangle of width min_gutter to
   // the left of bbox.
@@ -298,7 +301,12 @@ class TabFind : public AlignedBlob {
   void ComputeColumnWidths(ScrollView* tab_win,
                            ColPartitionGrid* part_grid);
 
-  // Find column width and pair-up tab vectors with existing ColPartitions.
+  // Finds column width and:
+  //   if col_widths is not null (pass1):
+  //     pair-up tab vectors with existing ColPartitions and accumulate widths.
+  //   else (pass2):
+  //     find the largest real partition width for each recorded column width,
+  //     to be used as the minimum acceptable width.
   void ApplyPartitionsToColumnWidths(ColPartitionGrid* part_grid,
                                      STATS* col_widths);
 
@@ -363,7 +371,8 @@ class TabFind : public AlignedBlob {
   TabVector_LIST vectors_;        //< List of rule line and tabstops.
   TabVector_IT v_it_;             //< Iterator for searching vectors_.
   TabVector_LIST dead_vectors_;   //< Separators and unpartnered tab vectors.
-  ICOORDELT_LIST column_widths_;  //< List of commonly occurring widths.
+  // List of commonly occuring width ranges with x=min and y=max.
+  ICOORDELT_LIST column_widths_;  //< List of commonly occurring width ranges.
   /** Callback to test an int for being a common width. */
   WidthCallback* width_cb_;
   // Sets of bounding boxes that are candidate tab stops.