TopOCR - Bringing Enhanced Tesseract OCR to Document Cameras
Tesseract LSTM OCR is a super accurate multi-lingual OCR classifier that has been optimized for TopOCR with greatly enhanced accuracy and speed compared to the standard release.
In addition to accuracy and speed enhancements, we've added a second OCR classifier to the Tesseract backend called "TAO OCR" or Tesseract Accelerated OCR. This will allow you to switch between two different text classifiers according to your own preference.
TAO OCR is derived from the same OCR engine used in Microsoft's "Seeing AI" application! However, instead of a phone app that executes through a cloud interface, TAO OCR executes MUCH more quickly directly on your PC, producing super accurate OCR that runs at warp speed! TAO OCR has been fully integrated into the Tesseract OCR system at the classifier level, allowing the user to easily select between either the standard LSTM OCR engine or the faster TAO OCR engine as Tesseract's main recognition engine for reading.
Tesseract LSTM OCR (LSTM Recurrent Neural Network + Static Classifier Architecture)
Tesseract LSTM OCR can read eleven different languages (English, Danish, Dutch, Finnish, French, German, Italian, Norwegian, Portuguese, Spanish, Swedish).
The primary character classifier function in Tesseract OCR is based on an implementation of a Long Short-Term Memory neural network or LSTM network.
LSTM neural networks outperform all other alternative neural network architecture models for this type of pattern recognition and also outperform the more "classical" character recognition algorithms used by the top selling commerical OCR products.
For example, an LSTM network achieved the best known results in unsegmented connected handwriting recognition, and in 2009 won the ICDAR handwriting competition.
If Tesseract's LSTM neural network recognizer fails on a particular character sequence, it can "fall-back" to its generic static shape classifier to make the determination.
So in essence, Tesseract LSTM is actually two OCR classifiers.
The amount of computation required for LSTM network character recognition is about 50 times greater than for character recognition performed using a static classifier. To help speed up the processing, we are utilizing either SSE4.2 or AVX instructions for the inner neural network calculations. We have also achieved a significant performance increase by making extensive use of multi-threading (running on multiple-CPUs) in the most CPU intensive portions of the OCR and image processing functions. To optimize multi-threading, TopOCR will automatically scale the number of threads the program uses based on the number of processors or "cores" on your PC. On a low-end DeskTop PC using a 4-core Intel 3.4GHz i7-6700 CPU, our implementation of Tesseract's LSTM neural network OCR engine takes about 6 seconds to read a 5.0 MP image and TopOCR's image pre-processing (binarization and straighten columns) adds about another second. Because of the enormous performance improvement achieved by using multi-processing, we recommend ONLY running TopOCR on a 4-core or better CPU! As 8-core and even 16-core and larger CPUs become more mainstream, TopOCR will be able to automatically scale it's performance for these CPUs!
Please note that in the latest release, Tesseract LSTM calculations will automatically switch to using the AVX instruction set if it is supported by your CPU, otherwise it will fallback to using the SSE4.2 or SSE special instruction sets.
TAO OCR - Tesseract Accelerated OCR
TAO OCR is a high performance multi-threaded, multilingual recognition engine that has been integrated into the Tesseract OCR System at the back-end classifier level.
TAO OCR takes document camera OCR to a whole new level by achieving scanner level accuracy at up to 10 times the speed of a scanner!
It relies upon Tesseract's low-level document layout analysis functions to collect fundamental page information that helps it perform operations like column straightening and automatic text orientation correction.
Compared to Tesseract's standard LSTM classifier, TAO OCR is significantly faster and almost as accurate, especially on lower quality camera images.
You can select either the TAO OCR classifier or the LSTM OCR classifier in the DocCam dialog or the OCR Settings dialog.
With a 4-core Intel 3.4GHz i7-6700 CPU, TAO OCR has an average reading speed of about 1.8 seconds per page for a 5.0 MP image.
This figure includes all image pre-processing and low-level document layout analysis.
The current version of TAO OCR has a skew tolerance of plus or minus 12 degrees and may reject pages that have skew angles greater than that.
TAO OCR can read curled book pages as well as pages that have poor lighting or poor contrast.
TAO OCR requires software libraries that are only available with Windows 10, so TAO OCR will not run on earlier versions of Windows.
TAO OCR supports all eleven TopOCR supported languages (English, Danish, Dutch, Finnish, French, German, Italian, Norwegian, Portuguese, Spanish, Swedish). However, it generally will only initially support the system language used by your OS. To add additional languages to TAO OCR, please see how to install a language pack for Windows 10.