Added section on Fine-tuning and LSTM model - example using Arabic

4.0-with-LSTM.md

@@ -13,7 +13,87 @@ Slides
 [#7](https://github.com/tesseract-ocr/docs/blob/master/das_tutorial2016/7Building%20a%20Multi-Lingual%20OCR%20Engine.pdf)
 have information about LSTM integration in Tesseract 4.0.
 
-## 3.05-dev
+## Fine-tuning and LSTM model - example using Arabic
+
+Have copies of the 4.0.0 alpha langdata, tessdata and tesseract-ocr repositories in the following directory structure.
+
+```
+./langdata
+./tessdata
+./tesseract-ocr
+./tesseract-ocr/tessdata
+./tesseract-ocr/tessdata/configs/
+```
+
+Make a copy of English and Arabic 4.0.0alpha traineddata files in ./tesseract-ocr/tessdata
+Check that lstm.train is available under configs.
+Setup appropriate TESSDATA_PREFIX directory.
+```
+cp ./tessdata/eng.traineddata ./tesseract-ocr/tessdata
+cp ./tessdata/ara.traineddata ./tesseract-ocr/tessdata
+```
+
+Change to the tesseract-ocr directory and then follow the given commands.
+
+```
+cd ./tesseract-ocr
+
+training/tesstrain.sh --fonts_dir /usr/share/fonts --lang ara  --linedata_only \
+  --training_text ../langdata/ara/arabic1.txt \
+  --langdata_dir ../langdata --tessdata_dir ./tessdata \
+  --fontlist "Times New Roman," \
+  --output_dir ~/tesstutorial/aratest
+```
+This creates the .lstmf files in the output directory. The box/tiff pairs are created in a /tmp/../ara/ directory and are not copied to the output directory.
+```
+mkdir -p ~/tesstutorial/aratuned_from_ara 
+
+combine_tessdata -e ../tessdata/ara.traineddata \
+  ~/tesstutorial/aratuned_from_ara/ara.lstm
+  
+lstmtraining --model_output ~/tesstutorial/aratuned_from_ara/aratuned \
+  --continue_from ~/tesstutorial/aratuned_from_ara/ara.lstm \
+  --train_listfile ~/tesstutorial/aratest/ara.training_files.txt \
+  --target_error_rate 0.01 
+```
+
+The above commands extract the existing LSTM model for Arabic from ./tessdata and finetune it using the .lstmf files created earlier, given in the train_listfile.
+``` 
+lstmtraining --model_output ~/tesstutorial/aratuned_from_ara/aratuned.lstm \
+  --continue_from ~/tesstutorial/aratuned_from_ara/aratuned_checkpoint \
+  --stop_training
+```
+The above command creates the new LSTM model from the finetuning output.
+```
+combine_tessdata -o ./tessdata/ara.traineddata \
+  ~/tesstutorial/aratuned_from_ara/aratuned.lstm \
+  ~/tesstutorial/aratest/ara.lstm-number-dawg \
+  ~/tesstutorial/aratest/ara.lstm-punc-dawg \
+  ~/tesstutorial/aratest/ara.lstm-word-dawg 
+```  
+Finally the new LSTM model and new dawg files can be combined with the existing Arabic traineddata in ./tesseract-ocr/tessdata. The old ara.traineddata file in ./tesseract-ocr/tessdata is renamed.
+
+```
+training/lstmeval --model ~/tesstutorial/aratuned_from_ara/ara.lstm \
+  --eval_listfile ~/tesstutorial/aratest/ara.training_files.txt  
+  
+training/lstmeval --model ~/tesstutorial/aratuned_from_ara/aratuned_checkpoint \
+  --eval_listfile ~/tesstutorial/aratest/ara.training_files.txt  
+  
+training/lstmeval --model ~/tesstutorial/aratuned_from_ara/aratuned.lstm \
+  --eval_listfile ~/tesstutorial/aratest/ara.training_files.txt  
+``` 
+
+The above three commands evaluate the LSTM models, first with the original Arabic LSTM model, second with the checkpoint model during finetuning and third with the finetuned Arabic model.
+
+```
+time tesseract --tessdata-dir ../tessdata /tmp/<tmpdir.ara/ara.Times_New_Roman.exp0.tif out-4alpha.txt -l ara
+time tesseract --tessdata-dir ./tessdata /tmp/<tmpdir>/ara/ara.Times_New_Roman.exp0.tif out-tuned.txt -l ara  
+```
+
+The above runs OCR on the tif file created during training with the original traineddata and finetuned traineddata 
+
+## 3.05-dev and 4.0.0-alpha for Windows
 
 An unofficial installer for Tesseract 3.05-dev for Windows is available from [Tesseract at UB Mannheim] (https://github.com/UB-Mannheim/tesseract/wiki). This includes the training tools.