Multi-page document recognition settings

Aspose.OCR for Java allows for very flexible customization of recognition accuracy, performance, and other settings by configuring the properties of the DocumentRecognitionSettings object.

These settings are applicable when extracting text from multi-page TIFF images and scanned PDF documents.

Method Parameter Default state Description
setAllowedCharacters Case-sensitive string of characters or one of the predefined character sets:
  • CharactersAllowedType.ALL - try to recognize all characters.
  • CharactersAllowedType.LATIN_ALPHABET - only recognize case-insensitive Latin / English text (A to Z and a to z), without accented characters.
  • CharactersAllowedType.DIGITS - recognize only binary, octal, decimal, or hexadecimal numbers (0-9 and A to F).
All characters from the selected recognition language. The whitelist of characters Aspose.OCR engine will look for.
  • true - enable
  • false - disable
Disabled Automatically increase the contrast of images before proceeding to recognition.
  • true - enable
  • false - disable
Disabled Automatically remove noise from images before proceeding to recognition.
  • true - enable
  • false - disable
Enabled Automatically correct image tilt (deskew) before proceeding to recognition.
  • true - enable
  • false - disable
Enabled Automatically select the optimal areas detection algorithm that suits the most common use cases.
setDetectAreasMode DetectAreasMode Automatic Manually override the default document areas detection method.
setIgnoredCharacters Case-sensitive string of characters All characters are recognized A blacklist of characters that are ignored during recognition.
setLanguage Recognition language Extended Latin characters, including diacritics Specify a language for recognition.
  • true - enable
  • false - disable
Enabled Set to true to recognize text in tables.
Set to false to improve performance by ignoring table structures and treating tables as plain text.
setPagesNumber Number of pages, int 1 The number of pages to be recognized in a multi-page file.
setSkew Skew angle, double 0 Manually rotate the image by the specified degree.
setStartPage Page number, int First page The page number from which to start recognition of the multi-page file. The first page number is 0.
setThreadsCount Number of threads, int Automatic The number of CPU threads used for recognition.
setThresholdValue Binarization threshold, int Automatic Override the automatic binarization settings.
  • true - enable
  • false - disable
Disabled Improve small font recognition and detection of dense lines.

Applicable to


The following code example shows how to fine-tune recognition:

// Create instance of OCR API
AsposeOCRPdf api = new AsposeOCRPdf();
// Specify recognition settings
DocumentRecognitionSettings recognitionSettings = new DocumentRecognitionSettings();
// Extract text from image
ArrayList<RecognitionResult> results = api.RecognizePdf("source.pdf", recognitionSettings);
// Save results to Microsoft Word document
AsposeOCR ocr = new AsposeOCR();
ocr.SaveMultipageDocument("result.docx", Format.Docx, results);