Third-party software integration: OCR
Starting with OpenKM 5.1.9 you can choose between several OCR engines:
| OCR Engine | Text Extractor | Image Formats | Program arguments |
|---|---|---|---|
| Tesseract 2.x | com.openkm.extractor.Tesseract2TextExtractor | TIFF | /path/to/tesseract ${fileIn} ${fileOut} |
| Tesseract 3.x | com.openkm.extractor.Tesseract3TextExtractor | TIFF PNG JPG GIF | /path/to/tesseract ${fileIn} ${fileOut} |
| Cuneiform | com.openkm.extractor.CuneiformTextExtractor | TIFF PNG JPG GIF | /path/to/cuneiform ${fileIn} -o ${fileOut} |
| Abby | com.openkm.extractor.AbbyTextExtractor | TIFF PNG JPG GIF | /path/to/abby ${fileIn} -o ${fileOut} |
 |
Check this Linux OCR Software Comparison. |
So, if you want to pass a command line parameter to your tesseract executable, you should use this configuration:
system.ocr=/usr/bin/tesseract ${fileIn} ${fileOut} -l esp
 |
You need to modify the registered.text.extractors configuration property to match the OCR engine you have configured using system.ocr. By default only Cuneiform text extractor is enabled. If you want to configure Tesseract remove the Cuneiform extractor and add the Tesseract extractor. |
You can also use an OpenOffice.org dictionary to enhance the OCR process. You can find these language specific dictionaries at OpenOffice.org Dictionary Repository. After download, set this configuration property with the path to the dictorionay file:
system.openoffice.dictionary=/path/to/dictionary.(oxt|zip)
Since OpenKM 5.1.10 you have a new configuration property which make possible to perform OCR in upside down scanned pages. This optional configuration property is called system.ocr.rotate and is defined as a list of degrees to rotate the pages. For example:
system.ocr.rotate=90;180;270;
Software required
You can enable any of these text extractors adding it in the textFilterClasses param of the SearchIndex section in your repository.xml file.
Starting with OpenKM 5.1 we offer integration with Cognitive OpenOCR (Cuneiform). This OCR engine make a very good job improving Tesseract conversion ratios.
Older OpenKM versions
Starting from OpenKM 5.1.8 Cuneiform configuration was changed and the parameters are, set in system.ocr configuration. Should be set to "/usr/bin/cuneiform ${fileIn} -o ${fileOut}". See Migration from 5.1.7 to 5.1.8 for more info. In older OpenKM releases the right configuration was "/usr/bin/cuneiform".
Starting from OpenKM 5.1.9 Tesseract configuration has changed and the parameters are, set in system.ocr configuration. Should be set to "/usr/bin/tesseract ${fileIn} ${fileOut}". See Migration from 5.1.8 to 5.1.9 for more info. In older OpenKM releases the right configuration was "/usr/bin/tesseract".
