Recognition settings

Aspose.OCR for .NET provides good recognition accuracy and performance by default. However, there will inevitably be cases where the default settings cannot provide reliable recognition results.

To configure Aspose.OCR recognition settings, pass an optional RecognitionSettings structure to the recognition method.

Setting	Type	Default value	Description
all_image	bool	false	Force recognition of the entire image. Not used for receipt recognition.
allowed_characters	characters_allowed_type	characters_allowed_type::ALL	The predefined whitelist of characters Aspose.OCR engine will look for.
alphabet	string	All symbols	A custom list of characters to be recognized, provided as a case-sensitive string. Characters that do not match the provided list are ignored.
auto_contrast	bool	false	Automatically increase the contrast of images before proceeding to recognition.
auto_denoising	bool	false	Automatically remove noise from images before proceeding to recognition.
correct_skew	bool	true	Automatically correct image tilt (deskew) before proceeding to recognition.
detect_areas_mode	detect_areas_mode_enum	detect_areas_mode_enum::DOCUMENT	Manually override the default document areas detection method. Not used for receipt recognition.
filters	custom_preprocessing_filters	none	Preprocessing filters to be applied to the image.
format	export_format	export_format::text	The format of recognition results that are stored in memory (plain text, JSON or XML).
ignoredCharacters	string	none	A blacklist of characters that are ignored during recognition.
language_alphabet	language	language::none	Specify a language for recognition.
lines_filtration	bool	false	Set to true to recognize text in tables. Set to false to improve performance by ignoring table structures and treating tables as plain text.
preprocess_area	rect*	NULL	Specify the image region to be affected by preprocessing filters.
rectangles	rect*	NULL	Areas of the image from which to extract text.
rectangles_size	size_t	0	The number of recognition areas.
save_format	file_format	file_format::txt	The file format in which the recognition result is saved.
skew	double	0	Manually rotate the image by the specified degree. Does not work if recognition areas are specified.
threshold_value	int	0	Override the automatic binarization settings.
upscale_small_font	bool	false	Improve small font recognition and detection of dense lines.

Example

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

std::string image_path = "source.png";
const size_t len = 4096;
wchar_t buffer[len] = { 0 };
RecognitionSettings settings;
settings.language_alphabet = language::ukr;
settings.auto_contrast = true;
settings.upscale_small_font = true;
size_t res_len = aspose::ocr::page_settings(image_path.c_str(), buffer, len, settings);
std::wcout << buffer;