Add a new renderer to create box files from images for LSTM training

src/api/Makefile.am

@@ -35,6 +35,7 @@ endif
 libtesseract_api_la_SOURCES = baseapi.cpp capi.cpp
 libtesseract_api_la_SOURCES += altorenderer.cpp
 libtesseract_api_la_SOURCES += hocrrenderer.cpp
+libtesseract_api_la_SOURCES += lstmboxrenderer.cpp
 libtesseract_api_la_SOURCES += pdfrenderer.cpp
 libtesseract_api_la_SOURCES += renderer.cpp
 

src/api/baseapi.h

@@ -613,6 +613,14 @@ class TESS_API TessBaseAPI {
    * Returned string must be freed with the delete [] operator.
    */
   char* GetTSVText(int page_number);
+
+  /**
+   * Make a box file for LSTM training from the internal data structures.
+   * Constructs coordinates in the original image - not just the rectangle.
+   * page_number is a 0-based page index that will appear in the box file.
+   * Returned string must be freed with the delete [] operator.
+   */
+  char* GetLSTMBOXText(int page_number);
 
   /**
    * The recognized text is returned as a char* which is coded in the same

src/api/hocrrenderer.cpp

@@ -268,7 +268,7 @@ char* TessBaseAPI::GetHOCRText(ETEXT_DESC* monitor, int page_number) {
       if (grapheme && grapheme[0] != 0) {
         if (hocr_boxes) {
           res_it->BoundingBox(RIL_SYMBOL, &left, &top, &right, &bottom);
-          hocr_str << "<span class='ocrx_cinfo' title='x_bboxes "
+          hocr_str << "\n             <span class='ocrx_cinfo' title='x_bboxes "
                    << left << " " << top << " " << right << " " << bottom
                    << "; x_conf " << res_it->Confidence(RIL_SYMBOL) << "'>";
         }

src/api/lstmboxrenderer.cpp

@@ -0,0 +1,111 @@
+/**********************************************************************
+ * File:        lstmboxrenderer.cpp
+ * Description: Renderer for creating box file for LSTM training.
+ *              based on the lstm_box renderer.
+ *
+ * (C) Copyright 2006, 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.
+ *
+ **********************************************************************/
+
+
+#include <locale>     // for std::locale::classic
+#include <memory>     // for std::unique_ptr
+#include <sstream>    // for std::stringstream
+#include "baseapi.h"  // for TessBaseAPI
+#include "renderer.h"
+#include "tesseractclass.h"  // for Tesseract
+
+namespace tesseract {
+
+/**
+ * Create a UTF8 box file for LSTM training from the internal data structures.
+ * page_number is a 0-base page index that will appear in the box file.
+ * Returned string must be freed with the delete [] operator.
+ */
+
+char* TessBaseAPI::GetLSTMBOXText(int page_number) {
+  if (tesseract_ == nullptr || (page_res_ == nullptr && Recognize(nullptr) < 0))
+    return nullptr;
+
+  STRING lstm_box_str("");
+
+  int page_num = page_number;
+  bool first_word = true;
+
+  LTRResultIterator* res_it = GetLTRIterator();
+  while (!res_it->Empty(RIL_BLOCK)) {
+    if (res_it->Empty(RIL_SYMBOL)) {
+      res_it->Next(RIL_SYMBOL);
+      continue;
+    }
+
+    int left, top, right, bottom;
+
+      if (!first_word) {
+    if (res_it->IsAtBeginningOf(RIL_WORD)) {
+        lstm_box_str.add_str_int("  ", left);
+        lstm_box_str.add_str_int(" ", image_height_ - bottom);
+        lstm_box_str.add_str_int(" ", right + 2);
+        lstm_box_str.add_str_int(" ", image_height_ - top);
+        lstm_box_str.add_str_int(" ", page_num);  // level 5 - word
+        lstm_box_str += "\n";  // end of row for word
+    }
+    if (res_it->IsAtBeginningOf(RIL_TEXTLINE)) {
+        lstm_box_str.add_str_int("\t ", left);
+        lstm_box_str.add_str_int(" ", image_height_ - bottom);
+        lstm_box_str.add_str_int(" ", right  + 5);
+        lstm_box_str.add_str_int(" ", image_height_ - top);
+        lstm_box_str.add_str_int(" ", page_num);  // level 4 - line
+        lstm_box_str += "\n";  // end of row for line
+    }
+    }
+    first_word=false;
+    res_it->BoundingBox(RIL_SYMBOL, &left, &top, &right, &bottom);
+
+    do {
+        lstm_box_str +=std::unique_ptr<const char[]>(res_it->GetUTF8Text(RIL_SYMBOL)).get();
+        res_it->Next(RIL_SYMBOL);
+    } while (!res_it->Empty(RIL_BLOCK) && !res_it->IsAtBeginningOf(RIL_SYMBOL));
+
+    lstm_box_str.add_str_int(" ", left);
+    lstm_box_str.add_str_int(" ", image_height_ - bottom);
+    lstm_box_str.add_str_int(" ", right);
+    lstm_box_str.add_str_int(" ", image_height_ - top);
+    lstm_box_str.add_str_int(" ", page_num);  // level 6 - symbol
+    lstm_box_str += "\n";  // end of row
+
+
+  }
+
+  char* ret = new char[lstm_box_str.length() + 1];
+  strcpy(ret, lstm_box_str.string());
+  delete res_it;
+  return ret;
+}
+
+/**********************************************************************
+ * LSTMBOX Renderer interface implementation
+ **********************************************************************/
+TessLSTMBOXRenderer::TessLSTMBOXRenderer(const char *outputbase)
+    : TessResultRenderer(outputbase, "box") {
+}
+
+bool TessLSTMBOXRenderer::AddImageHandler(TessBaseAPI* api) {
+  const std::unique_ptr<const char[]> lstmbox(api->GetLSTMBOXText(imagenum()));
+  if (lstmbox == nullptr) return false;
+
+  AppendString(lstmbox.get());
+
+  return true;
+}
+
+}  // namespace tesseract.

src/api/renderer.h

@@ -247,6 +247,17 @@ class TESS_API TessUnlvRenderer : public TessResultRenderer {
   virtual bool AddImageHandler(TessBaseAPI* api);
 };
 
+/**
+ * Renders tesseract output into a plain UTF-8 text string for LSTMBOX
+ */
+class TESS_API TessLSTMBOXRenderer : public TessResultRenderer {
+ public:
+  explicit TessLSTMBOXRenderer(const char *outputbase);
+
+ protected:
+  virtual bool AddImageHandler(TessBaseAPI* api);
+};
+
 /**
  * Renders tesseract output into a plain UTF-8 text string
  */

src/api/tesseractmain.cpp

@@ -494,6 +494,20 @@ static void PreloadRenderers(
       }
     }
 
+    api->GetBoolVariable("tessedit_create_lstmbox", &b);
+    if (b) {
+      tesseract::TessLSTMBOXRenderer* renderer =
+        new tesseract::TessLSTMBOXRenderer(outputbase);
+      if (renderer->happy()) {
+        renderers->push_back(renderer);
+      } else {
+        delete renderer;
+        tprintf("Error, could not create LSTM BOX output file: %s\n",
+                strerror(errno));
+        error = true;
+      }
+    }
+
     api->GetBoolVariable("tessedit_create_boxfile", &b);
     if (b) {
       tesseract::TessBoxTextRenderer* renderer =

src/ccmain/tesseractclass.cpp

@@ -391,6 +391,8 @@ Tesseract::Tesseract()
                   this->params()),
       BOOL_MEMBER(tessedit_create_alto, false, "Write .xml ALTO file",
                   this->params()),
+      BOOL_MEMBER(tessedit_create_lstmbox, false, "Write .box file for LSTM training",
+                  this->params()),
       BOOL_MEMBER(tessedit_create_tsv, false, "Write .tsv output file",
                   this->params()),
       BOOL_MEMBER(tessedit_create_pdf, false, "Write .pdf output file",

src/ccmain/tesseractclass.h

@@ -1040,6 +1040,7 @@ class Tesseract : public Wordrec {
   BOOL_VAR_H(tessedit_create_txt, false, "Write .txt output file");
   BOOL_VAR_H(tessedit_create_hocr, false, "Write .html hOCR output file");
   BOOL_VAR_H(tessedit_create_alto, false, "Write .xml ALTO output file");
+  BOOL_VAR_H(tessedit_create_lstmbox, false, "Write .box file for LSTM training");
   BOOL_VAR_H(tessedit_create_tsv, false, "Write .tsv output file");
   BOOL_VAR_H(tessedit_create_pdf, false, "Write .pdf output file");
   BOOL_VAR_H(textonly_pdf, false,

tessdata/configs/lstmbox

@@ -0,0 +1 @@
+tessedit_create_lstmbox 1