An experiment in the recognition of handwritten texts in Cyrillic

Introduction

Handwritten Text Recognition (HTR) is an automatic way to transcribe records using a computer. The digitized form of handwritten notes would automate the business processes of many companies, making human work easier. In this paper, we consider a model for recognizing handwritten text in Cyrillic based on an artificial neural network. The study used the SimpleHTR system developed by Harald, as well as LineHTR , an extended version of the Simple HTR system  . You can read more about SimpleHTR here .

Dataset

In this section, I will describe two types of datasets: The first dataset contains handwritten quotes in Cyrillic. It contains 21,000 images from various handwriting samples (names of countries and cities). We augmented this training dataset by collecting 207,438 images from available shapes or samples.

The second HKR for the handwritten Kazakh-Russian database consisted of single words (or short phrases) written in Russian and Kazakh (about 95% Russian and 5% Kazakh word / sentence, respectively). Note that both languages ​​are Cyrillic written and share the same 33 characters. In addition to these symbols, there are 9 more specific symbols in the Kazakh alphabet. Some examples of the HKR dataset are shown below: 

(70%), (15%) (15%) . ( 7,5% ): TEST1 , ; TEST2 , , . TEST1 TEST2 , , .

SimpleHTR

ANN, CNN . RNN. RNN . RNN . RNN. CTC . . CTC ; RNN , . CTC . , , , . , , , , .

: CNN: CNN. . 55 33 . RELU , , . 2 , () , ( ) 32 256. RNN: 256 . . LSTM- RNN, , . RNN 3280.

CTC: RNN , . CTC . 32

: : 128 32. , ( ) , 128 32 . 128 32 . , .

LineHTR

LineHTR - SimpleHTR, , ( ), , . LineHTR SimpleHTR, CNN RNN : 7 CNN 2 Bidirectinal LSTM (BLSTM) RNN. 

LineHTR:

• 800 x 64 ( x ).

  
  
  
  
  

• CNN 100 x 512.

  
  
  
  
  

• BLSTM 512 100 x 205: 100 ( ) ; 205 )

  
  
  
  
  

• CTC 2 : LOSS - ; -

  
  
  
  
  

• 50

  
  
  
  
  

Python deep learning Tensorflow. Tensorflow Python. Python , . matplotlib Python, Inkscape- , Adobe Photoshop. 2- " Intel ® Xeon(R) E-5-2680”, 4x " NVIDIA Tesla k20x” 100 RAM. 3 , , .

SimpleHTR

SimpleHTR - , . , :

•

• DataLoader

• : 90% 10% . : -, , ; -, CNN ; -, ; -, , , , .

: SimpleHTR, 42 . 10 . : . , .

SimpleHTR (bestpath, beamsearch, wordbeamsearch). NN , . NN, , , . character-LM , .

:

, , " ” 86 .

(HKR Dataset): SimpleHTR 20,13% (CER) 1,55% CER. SimpleHTR ( ). (WER) 58,97% 1 11,09% 2. TEST2 . TEST1 , , , .

LineHTR, 100 . CAR 29,86% 86,71% TEST1 TEST2 ( ). .

SimpleHTR LineHTR : 57,1% SimpleHTR CNN , 58,3% Beamsearch 75,1% wordbeamsearch. Wordbeamsearch, .