tesseract::LineFinder Class Reference

#include <linefind.h>

Static Public Member Functions
static void	FindAndRemoveLines (int resolution, bool debug, Image pix, int *vertical_x, int *vertical_y, Image *pix_music_mask, TabVector_LIST *v_lines, TabVector_LIST *h_lines)

Detailed Description

The LineFinder class is a simple static function wrapper class that mainly exposes the FindVerticalLines function.

Definition at line 31 of file linefind.h.

Member Function Documentation

FindAndRemoveLines()

void tesseract::LineFinder::FindAndRemoveLines ( int  resolution, bool  debug, Image  pix, int *  vertical_x, int *  vertical_y, Image *  pix_music_mask, TabVector_LIST *  v_lines, TabVector_LIST *  h_lines  )

static

Finds vertical and horizontal line objects in the given pix and removes them.

Uses the given resolution to determine size thresholds instead of any that may be present in the pix.

The output vertical_x and vertical_y contain a sum of the output vectors, thereby giving the mean vertical direction.

If pix_music_mask != nullptr, and music is detected, a mask of the staves and anything that is connected (bars, notes etc.) will be returned in pix_music_mask, the mask subtracted from pix, and the lines will not appear in v_lines or h_lines.

The output vectors are owned by the list and Frozen (cannot refit) by having no boxes, as there is no need to refit or merge separator lines.

The detected lines are removed from the pix.

Definition at line 691 of file linefind.cpp.

                                                             {
  if (pix == nullptr || vertical_x == nullptr || vertical_y == nullptr) {
    tprintf("Error in parameters for LineFinder::FindAndRemoveLines\n");
    return;
  }
  Image pix_vline = nullptr;
  Image pix_non_vline = nullptr;
  Image pix_hline = nullptr;
  Image pix_non_hline = nullptr;
  Image pix_intersections = nullptr;
  Pixa *pixa_display = debug ? pixaCreate(0) : nullptr;
  GetLineMasks(resolution, pix, &pix_vline, &pix_non_vline, &pix_hline, &pix_non_hline,
               &pix_intersections, pix_music_mask, pixa_display);
  // Find lines, convert to TabVector_LIST and remove those that are used.
  FindAndRemoveVLines(pix_intersections, vertical_x, vertical_y, &pix_vline,
                      pix_non_vline, pix, v_lines);
  pix_intersections.destroy();
  if (pix_hline != nullptr) {
    // Recompute intersections and re-filter false positive h-lines.
    if (pix_vline != nullptr) {
      pix_intersections = pix_vline & pix_hline;
    }
    if (!FilterFalsePositives(resolution, pix_non_hline, pix_intersections, pix_hline)) {
      pix_hline.destroy();
    }
  }
  FindAndRemoveHLines(pix_intersections, *vertical_x, *vertical_y, &pix_hline,
                      pix_non_hline, pix, h_lines);
  if (pixa_display != nullptr && pix_vline != nullptr) {
    pixaAddPix(pixa_display, pix_vline, L_CLONE);
  }
  if (pixa_display != nullptr && pix_hline != nullptr) {
    pixaAddPix(pixa_display, pix_hline, L_CLONE);
  }
  pix_intersections.destroy();
  if (pix_vline != nullptr && pix_hline != nullptr) {
    // Remove joins (intersections) where lines cross, and the residue.
    // Recalculate the intersections, since some lines have been deleted.
    pix_intersections = pix_vline & pix_hline;
    // Fatten up the intersections and seed-fill to get the intersection
    // residue.
    Image pix_join_residue = pixDilateBrick(nullptr, pix_intersections, 5, 5);
    pixSeedfillBinary(pix_join_residue, pix_join_residue, pix, 8);
    // Now remove the intersection residue.
    pixSubtract(pix, pix, pix_join_residue);
    pix_join_residue.destroy();
  }
  // Remove any detected music.
  if (pix_music_mask != nullptr && *pix_music_mask != nullptr) {
    if (pixa_display != nullptr) {
      pixaAddPix(pixa_display, *pix_music_mask, L_CLONE);
    }
    pixSubtract(pix, pix, *pix_music_mask);
  }
  if (pixa_display != nullptr) {
    pixaAddPix(pixa_display, pix, L_CLONE);
  }
 
  pix_vline.destroy();
  pix_non_vline.destroy();
  pix_hline.destroy();
  pix_non_hline.destroy();
  pix_intersections.destroy();
  if (pixa_display != nullptr) {
    pixaConvertToPdf(pixa_display, resolution, 1.0f, 0, 0, "LineFinding", "vhlinefinding.pdf");
    pixaDestroy(&pixa_display);
  }
}

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

• /media/home/debian/src/github/tesseract-ocr/tesseract/src/textord/linefind.h
• /media/home/debian/src/github/tesseract-ocr/tesseract/src/textord/linefind.cpp