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/*
This file is part of the iText (R) project.
Copyright (c) 1998-2021 iText Group NV
Authors: iText Software.
This program is offered under a commercial and under the AGPL license.
For commercial licensing, contact us at https://itextpdf.com/sales. For AGPL licensing, see below.
AGPL licensing:
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see .
*/
package com.itextpdf.pdfocr.tesseract4;
import com.itextpdf.io.util.FileUtil;
import com.itextpdf.io.util.MessageFormatUtil;
import com.itextpdf.pdfocr.IOcrEngine;
import com.itextpdf.pdfocr.OcrEngineProperties;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.nio.charset.StandardCharsets;
import java.util.List;
import org.slf4j.LoggerFactory;
/**
* Properties that will be used by the {@link IOcrEngine}.
*/
public class Tesseract4OcrEngineProperties extends OcrEngineProperties {
/**
* Default suffix for user-word file.
* (e.g. name: 'eng.user-words')
*/
static final String DEFAULT_USER_WORDS_SUFFIX = "user-words";
/**
* Default language for OCR.
*/
private static final String DEFAULT_LANGUAGE = "eng";
/**
* Path to directory with tess data.
*/
private File tessDataDir;
/**
* Page Segmentation Mode.
*/
private Integer pageSegMode = 3;
/**
* Defines the way text is retrieved from tesseract output.
* Default text positioning is by lines.
*/
private TextPositioning textPositioning = TextPositioning.BY_LINES;
/**
* Path to the file containing user words.
* Each word should be on a new line,
* file should end with a newline character.
*/
private String pathToUserWordsFile = null;
/**
* Indicates if user words file is temporary and has to be removed.
*/
private boolean isUserWordsFileTemporary = false;
/**
* Used to make HOCR recognition result more precise.
* This is needed for cases of Thai language or some Chinese dialects
* where every character is interpreted as a single word.
* For more information see https://github.com/tesseract-ocr/tesseract/issues/2702
*/
private boolean useTxtToImproveHocrParsing;
/**
* Settings for image preprocessing.
*/
private ImagePreprocessingOptions imagePreprocessingOptions = new ImagePreprocessingOptions();
/**
* Minimal confidence level for HOCR line to be considered as properly recognized.
* If real confidence level is lower then line is ignored
* Default value is 0 which means that everything is considered as properly recognized
* Value may vary in range of 0-100
*/
private int minimalConfidenceLevel;
/**
* Creates a new {@link Tesseract4OcrEngineProperties} instance.
*/
public Tesseract4OcrEngineProperties() {
}
/**
* Creates a new {@link Tesseract4OcrEngineProperties} instance
* based on another {@link Tesseract4OcrEngineProperties} instance (copy
* constructor).
*
* @param other the other {@link Tesseract4OcrEngineProperties} instance
*/
public Tesseract4OcrEngineProperties(Tesseract4OcrEngineProperties other) {
super(other);
this.tessDataDir = other.tessDataDir;
this.pageSegMode = other.pageSegMode;
this.textPositioning = other.textPositioning;
this.pathToUserWordsFile = other.pathToUserWordsFile;
this.useTxtToImproveHocrParsing = other.useTxtToImproveHocrParsing;
this.imagePreprocessingOptions = other.imagePreprocessingOptions;
this.minimalConfidenceLevel = other.minimalConfidenceLevel;
}
/**
* Gets default language for ocr.
*
* @return default language - "eng"
*/
public final String getDefaultLanguage() {
return DEFAULT_LANGUAGE;
}
/**
* Gets default user words suffix.
*
* @return default suffix for user words files
*/
public final String getDefaultUserWordsSuffix() {
return DEFAULT_USER_WORDS_SUFFIX;
}
/**
* Gets path to directory with tess data.
*
* @return path to directory with tess data
*/
public final File getPathToTessData() {
return tessDataDir;
}
/**
* Sets path to directory with tess data.
*
* @param tessData path to train directory as {@link java.io.File}
* @return the {@link Tesseract4OcrEngineProperties} instance
* @throws Tesseract4OcrException if path to tess data directory is
* null or empty, or provided directory does not exist? or it is not
* a directory
*/
public final Tesseract4OcrEngineProperties setPathToTessData(
final File tessData) {
if (tessData == null
|| !FileUtil.directoryExists(tessData.getAbsolutePath())) {
throw new Tesseract4OcrException(
Tesseract4OcrException
.PATH_TO_TESS_DATA_DIRECTORY_IS_INVALID);
}
this.tessDataDir = tessData;
return this;
}
/**
* Gets Page Segmentation Mode.
*
* @return psm mode as {@link java.lang.Integer}
*/
public final Integer getPageSegMode() {
return pageSegMode;
}
/**
* Sets Page Segmentation Mode.
* More detailed explanation about psm modes could be found
* here https://github.com/tesseract-ocr/tesseract/blob/master/doc/tesseract.1.asc#options
* Note that in documentation it is stated that default value of PSM is 3.
* This is true for tesseract executable,
* but for tesseract lib it is -1 which has negative impact on some documents.
* That's why in the code we set it explicitly to 3.
*
* @param mode psm mode as {@link java.lang.Integer}
* @return the {@link Tesseract4OcrEngineProperties} instance
*/
public final Tesseract4OcrEngineProperties setPageSegMode(
final Integer mode) {
pageSegMode = mode;
return this;
}
/**
* Checks whether image preprocessing is needed.
*
* @return true if images need to be preprocessed, otherwise - false
*/
public final boolean isPreprocessingImages() {
return imagePreprocessingOptions != null;
}
/**
* Sets true if image preprocessing is needed.
*
* @param preprocess true if images need to be preprocessed,
* otherwise - false
* @return the {@link Tesseract4OcrEngineProperties} instance
*/
public final Tesseract4OcrEngineProperties setPreprocessingImages(
final boolean preprocess) {
if (preprocess) {
if (imagePreprocessingOptions == null) {
imagePreprocessingOptions = new ImagePreprocessingOptions();
}
} else {
imagePreprocessingOptions = null;
}
return this;
}
/**
* Defines the way text is retrieved from tesseract output using
* {@link TextPositioning}.
*
* @return the way text is retrieved
*/
public final TextPositioning getTextPositioning() {
return textPositioning;
}
/**
* Defines the way text is retrieved from tesseract output
* using {@link TextPositioning}.
*
* @param positioning the way text is retrieved
* @return the {@link Tesseract4OcrEngineProperties} instance
*/
public final Tesseract4OcrEngineProperties setTextPositioning(
final TextPositioning positioning) {
textPositioning = positioning;
return this;
}
/**
* Using provided list of words there will be created
* temporary file containing words (one per line) which
* ends with a new line character. Train data for provided language
* should exist in specified tess data directory.
*
* NOTE:
* User words dictionary doesn't work properly in tesseract4
* and hidden for public usage until fix is available
*
* @param language language as {@link java.lang.String}, tessdata for
* this languages has to exist in tess data directory
* @param userWords {@link java.util.List} of custom words
* @return the {@link Tesseract4OcrEngineProperties} instance
* @throws Tesseract4OcrException if one of given languages wasn't specified in the
* list of required languages for OCR using
*/
Tesseract4OcrEngineProperties setUserWords(final String language,
final List userWords)
throws Tesseract4OcrException {
setPathToUserWordsFile(null);
if (userWords != null && userWords.size() > 0) {
try {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
for (String word : userWords) {
byte[] bytesWord = word.getBytes();
baos.write(bytesWord, 0, bytesWord.length);
byte[] bytesSeparator = System.lineSeparator()
.getBytes();
baos.write(bytesSeparator, 0, bytesSeparator.length);
}
InputStream inputStream = new ByteArrayInputStream(
baos.toByteArray());
baos.close();
setUserWords(language, inputStream);
} catch (IOException e) {
LoggerFactory.getLogger(getClass())
.warn(MessageFormatUtil.format(
Tesseract4LogMessageConstant.CANNOT_USE_USER_WORDS,
e.getMessage()));
}
}
return this;
}
/**
* Using provided input stream there will be created
* temporary file (with name 'language.user-words')
* containing words (one per line) which ends with
* a new line character. Train data for provided language
* should exist in specified tess data directory.
*
* NOTE:
* User words dictionary doesn't work properly in tesseract4
* and hidden for public usage until fix is available
*
* @param language language as {@link java.lang.String}, tessdata for
* this languages has to exist in tess data directory
* @param inputStream custom user words as {@link java.io.InputStream}
* @throws Tesseract4OcrException if one of given languages wasn't specified
* in the list of required languages for OCR using
* {@link Tesseract4OcrEngineProperties#setLanguages(List)} method
* @return the {@link Tesseract4OcrEngineProperties} instance
*/
Tesseract4OcrEngineProperties setUserWords(final String language,
final InputStream inputStream) throws Tesseract4OcrException {
setPathToUserWordsFile(null);
if (!getLanguages().contains(language)) {
if (DEFAULT_LANGUAGE.equals(language.toLowerCase())) {
List languagesList = getLanguages();
languagesList.add(language);
setLanguages(languagesList);
} else {
throw new Tesseract4OcrException(
Tesseract4OcrException.LANGUAGE_IS_NOT_IN_THE_LIST)
.setMessageParams(language);
}
}
String userWordsFileName = TesseractOcrUtil.getTempFilePath(language,
"." + DEFAULT_USER_WORDS_SUFFIX);
try (OutputStreamWriter writer =
new FileWriter(userWordsFileName)) {
Reader reader = new InputStreamReader(inputStream,
StandardCharsets.UTF_8);
int data;
while ((data = reader.read()) != -1) {
writer.write(data);
}
writer.write(System.lineSeparator());
setPathToUserWordsFile(userWordsFileName, true);
} catch (IOException e) {
setPathToUserWordsFile(null);
LoggerFactory.getLogger(getClass())
.warn(MessageFormatUtil.format(
Tesseract4LogMessageConstant.CANNOT_USE_USER_WORDS,
e.getMessage()));
}
return this;
}
/**
* Returns path to the user words file.
*
* NOTE:
* User words dictionary doesn't work properly in tesseract4
* and hidden for public usage until fix is available
*
* @return path to user words file as {@link java.lang.String} if it
* exists, otherwise - null
*/
final String getPathToUserWordsFile() {
return pathToUserWordsFile;
}
/**
* Sets path to the user words file.
*
* NOTE:
* User words dictionary doesn't work properly in tesseract4
* and hidden for public usage until fix is available
*
* @param pathToUserWordsFile path to user words file
* as {@link java.lang.String}
* @return the {@link Tesseract4OcrEngineProperties} instance
*/
final Tesseract4OcrEngineProperties setPathToUserWordsFile(
String pathToUserWordsFile) {
return setPathToUserWordsFile(pathToUserWordsFile, false);
}
/**
* Sets path to the user words file.
*
* @param pathToUserWordsFile path to user words file
* as {@link java.lang.String}
* @param isTempFile indicates if user words file is temporary and has to be removed
* @return the {@link Tesseract4OcrEngineProperties} instance
*/
final Tesseract4OcrEngineProperties setPathToUserWordsFile(
String pathToUserWordsFile, boolean isTempFile) {
this.pathToUserWordsFile = pathToUserWordsFile;
this.isUserWordsFileTemporary = isTempFile;
return this;
}
/**
* Indicates if user words file is temporary and has to be removed.
*
* @return true if the file is temporary, otherwise false.
*/
final boolean isUserWordsFileTemporary() {
return isUserWordsFileTemporary;
}
/**
* Gets {@link #useTxtToImproveHocrParsing}.
* Used to make HOCR recognition result more precise.
* This is needed for cases of Thai language or some Chinese dialects
* where every character is interpreted as a single word.
* For more information see https://github.com/tesseract-ocr/tesseract/issues/2702
*
* @return {@link #useTxtToImproveHocrParsing}
*/
final public boolean isUseTxtToImproveHocrParsing() {
return useTxtToImproveHocrParsing;
}
/**
* Sets {@link #useTxtToImproveHocrParsing}.
* Used to make HOCR recognition result more precise.
* This is needed for cases of Thai language or some Chinese dialects
* where every character is interpreted as a single word.
* For more information see https://github.com/tesseract-ocr/tesseract/issues/2702
*
* @param useTxtToImproveHocrParsing {@link #useTxtToImproveHocrParsing}
*/
final public Tesseract4OcrEngineProperties setUseTxtToImproveHocrParsing(boolean useTxtToImproveHocrParsing) {
this.useTxtToImproveHocrParsing = useTxtToImproveHocrParsing;
return this;
}
/**
* Gets {@link #imagePreprocessingOptions}.
* @return {@link ImagePreprocessingOptions}
*/
final public ImagePreprocessingOptions getImagePreprocessingOptions() {
return imagePreprocessingOptions;
}
/**
* Sets {@link #imagePreprocessingOptions}.
* @param imagePreprocessingOptions {@link ImagePreprocessingOptions}
* @return the {@link Tesseract4OcrEngineProperties} instance
*/
final public Tesseract4OcrEngineProperties setImagePreprocessingOptions(
ImagePreprocessingOptions imagePreprocessingOptions) {
this.imagePreprocessingOptions = imagePreprocessingOptions;
return this;
}
/**
* Gets minimal confidence level for HOCR line to be considered as properly recognized.
* If real confidence level is lower then line is ignored
* Default value is 0 which means that everything is considered as properly recognized
* Value may vary in range of 0-100
*/
final public int getMinimalConfidenceLevel() {
return minimalConfidenceLevel;
}
/**
* Sets minimal confidence level for HOCR line to be considered as properly recognized.
* If real confidence level is lower then line is ignored
* Default value is 0 which means that everything is considered as properly recognized
* Value may vary in range of 0-100
*/
final public Tesseract4OcrEngineProperties setMinimalConfidenceLevel(int minimalConfidenceLevel) {
this.minimalConfidenceLevel = minimalConfidenceLevel;
return this;
}
}
