/// <summary>
/// Gets OCR result from provided multi-page image and returns result as
/// list of strings for each page.
/// </summary>
/// <remarks>
/// Gets OCR result from provided multi-page image and returns result as
/// list of strings for each page. This method is used for tiff images
/// when preprocessing is not needed.
/// </remarks>
/// <param name="inputImage">
/// input image
/// <see cref="System.IO.FileInfo"/>
/// </param>
/// <param name="outputFormat">
/// selected
/// <see cref="OutputFormat"/>
/// for tesseract
/// </param>
/// <returns>
/// list of result string that will be written to a temporary files
/// later
/// </returns>
private IList <String> GetOcrResultForMultiPage(FileInfo inputImage, OutputFormat outputFormat)
{
IList <String> resultList = new List <String>();
try {
InitializeTesseract(outputFormat);
TesseractOcrUtil util = new TesseractOcrUtil();
util.InitializeImagesListFromTiff(inputImage);
int numOfPages = util.GetListOfPages().Count;
for (int i = 0; i < numOfPages; i++)
{
String result = util.GetOcrResultAsString(GetTesseractInstance(), util.GetListOfPages()[i], outputFormat);
resultList.Add(result);
}
}
catch (TesseractException e) {
String msg = MessageFormatUtil.Format(Tesseract4LogMessageConstant.TESSERACT_FAILED, e.Message);
LogManager.GetLogger(GetType()).Error(msg);
throw new Tesseract4OcrException(Tesseract4OcrException.TESSERACT_FAILED);
}
finally {
TesseractOcrUtil.DisposeTesseractInstance(GetTesseractInstance());
}
return(resultList);
}
/// <summary>
/// Performs tesseract OCR using wrapper for Tesseract OCR API for the selected page
/// of input image (by default 1st).
/// </summary>
/// <remarks>
/// Performs tesseract OCR using wrapper for Tesseract OCR API for the selected page
/// of input image (by default 1st).
/// Please note that list of output files is accepted instead of a single file because
/// page number parameter is not respected in case of TIFF images not requiring preprocessing.
/// In other words, if the passed image is the TIFF image and according to the
/// <see cref="Tesseract4OcrEngineProperties"/>
/// no preprocessing is needed, each page of the TIFF image is OCRed and the number of output files in the list
/// is expected to be same as number of pages in the image, otherwise, only one file is expected
/// </remarks>
/// <param name="inputImage">
/// input image
/// <see cref="System.IO.FileInfo"/>
/// </param>
/// <param name="outputFiles">
///
/// <see cref="System.Collections.IList{E}"/>
/// of output files
/// (one per each page)
/// </param>
/// <param name="outputFormat">
/// selected
/// <see cref="OutputFormat"/>
/// for tesseract
/// </param>
/// <param name="pageNumber">number of page to be processed</param>
internal override void DoTesseractOcr(FileInfo inputImage, IList <FileInfo> outputFiles, OutputFormat outputFormat
, int pageNumber)
{
ScheduledCheck();
try {
ValidateLanguages(GetTesseract4OcrEngineProperties().GetLanguages());
InitializeTesseract(outputFormat);
OnEvent();
// if preprocessing is not needed and provided image is tiff,
// the image will be paginated and separate pages will be OCRed
IList <String> resultList = new List <String>();
if (!GetTesseract4OcrEngineProperties().IsPreprocessingImages() && ImagePreprocessingUtil.IsTiffImage(inputImage
))
{
resultList = GetOcrResultForMultiPage(inputImage, outputFormat);
}
else
{
resultList.Add(GetOcrResultForSinglePage(inputImage, outputFormat, pageNumber));
}
// list of result strings is written to separate files
// (one for each page)
for (int i = 0; i < resultList.Count; i++)
{
String result = resultList[i];
FileInfo outputFile = i >= outputFiles.Count ? null : outputFiles[i];
if (result != null && outputFile != null)
{
try {
using (TextWriter writer = new StreamWriter(new FileStream(outputFile.FullName, FileMode.Create), System.Text.Encoding
.UTF8)) {
writer.Write(result);
}
}
catch (System.IO.IOException e) {
LogManager.GetLogger(GetType()).Error(MessageFormatUtil.Format(Tesseract4LogMessageConstant.CANNOT_WRITE_TO_FILE
, e.Message));
throw new Tesseract4OcrException(Tesseract4OcrException.TESSERACT_FAILED);
}
}
}
}
catch (Tesseract4OcrException e) {
LogManager.GetLogger(GetType()).Error(e.Message);
throw new Tesseract4OcrException(e.Message, e);
}
finally {
if (tesseractInstance != null)
{
TesseractOcrUtil.DisposeTesseractInstance(tesseractInstance);
}
if (GetTesseract4OcrEngineProperties().GetPathToUserWordsFile() != null && GetTesseract4OcrEngineProperties
().IsUserWordsFileTemporary())
{
TesseractHelper.DeleteFile(GetTesseract4OcrEngineProperties().GetPathToUserWordsFile());
}
}
}
