/////////////////////////////////////////////////////////////////////// // File: linefind.h // Description: Class to find vertical lines in an image and create // a corresponding list of empty blobs. // Author: Ray Smith // Created: Thu Mar 20 09:49:01 PDT 2008 // // (C) Copyright 2008, Google Inc. // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // http://www.apache.org/licenses/LICENSE-2.0 // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. // /////////////////////////////////////////////////////////////////////// #ifndef TESSERACT_TEXTORD_LINEFIND_H__ #define TESSERACT_TEXTORD_LINEFIND_H__ struct Boxa; struct Pix; struct Pixa; class C_BLOB_LIST; class BLOBNBOX_LIST; class ICOORD; namespace tesseract { class TabVector_LIST; /** * The LineFinder class is a simple static function wrapper class that mainly * exposes the FindVerticalLines function. */ class LineFinder { public: /** * 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 != NULL, 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. */ static void FindAndRemoveLines(int resolution, bool debug, Pix* pix, int* vertical_x, int* vertical_y, Pix** pix_music_mask, TabVector_LIST* v_lines, TabVector_LIST* h_lines); /** * Converts the Boxa array to a list of C_BLOB, getting rid of severely * overlapping outlines and those that are children of a bigger one. * * The output is a list of C_BLOBs that are owned by the list. * * The C_OUTLINEs in the C_BLOBs contain no outline data - just empty * bounding boxes. The Boxa is consumed and destroyed. */ static void ConvertBoxaToBlobs(int image_width, int image_height, Boxa** boxes, C_BLOB_LIST* blobs); private: // Finds vertical line objects in pix_vline and removes them from src_pix. // 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. // 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. // If no good lines are found, pix_vline is destroyed. static void FindAndRemoveVLines(int resolution, Pix* pix_intersections, int* vertical_x, int* vertical_y, Pix** pix_vline, Pix* pix_non_vline, Pix* src_pix, TabVector_LIST* vectors); // Finds horizontal line objects in pix_vline and removes them from src_pix. // 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. // 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. // If no good lines are found, pix_hline is destroyed. static void FindAndRemoveHLines(int resolution, Pix* pix_intersections, int vertical_x, int vertical_y, Pix** pix_hline, Pix* pix_non_hline, Pix* src_pix, TabVector_LIST* vectors); // Finds vertical lines in the given list of BLOBNBOXes. bleft and tright // are the bounds of the image on which the input line_bblobs were found. // The input line_bblobs list is const really. // The output vertical_x and vertical_y are the total of all the vectors. // The output list of TabVector makes no reference to the input BLOBNBOXes. static void FindLineVectors(const ICOORD& bleft, const ICOORD& tright, BLOBNBOX_LIST* line_bblobs, int* vertical_x, int* vertical_y, TabVector_LIST* vectors); // Most of the heavy lifting of line finding. Given src_pix and its separate // resolution, returns image masks: // Returns image masks: // pix_vline candidate vertical lines. // pix_non_vline pixels that didn't look like vertical lines. // pix_hline candidate horizontal lines. // pix_non_hline pixels that didn't look like horizontal lines. // pix_intersections pixels where vertical and horizontal lines meet. // pix_music_mask candidate music staves. // This function promises to initialize all the output (2nd level) pointers, // but any of the returns that are empty will be NULL on output. // None of the input (1st level) pointers may be NULL except pix_music_mask, // which will disable music detection, and pixa_display, which is for debug. static void GetLineMasks(int resolution, Pix* src_pix, Pix** pix_vline, Pix** pix_non_vline, Pix** pix_hline, Pix** pix_non_hline, Pix** pix_intersections, Pix** pix_music_mask, Pixa* pixa_display); // Returns a list of boxes corresponding to the candidate line segments. Sets // the line_crossings member of the boxes so we can later determin the number // of intersections touched by a full line. static void GetLineBoxes(bool horizontal_lines, Pix* pix_lines, Pix* pix_intersections, C_BLOB_LIST* line_cblobs, BLOBNBOX_LIST* line_bblobs); }; } // namespace tesseract. #endif // TESSERACT_TEXTORD_LINEFIND_H__