com.itextpdf.pdfocr.tesseract4.ImagePreprocessingUtil Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of pdfocr-tesseract4 Show documentation
Show all versions of pdfocr-tesseract4 Show documentation
pdfOCR-Tesseract4 is an iText add-on for Java to recognize and extract text in scanned documents and images. It can also convert them into fully ISO-compliant PDF or PDF/A-3u files that are accessible, searchable, and suitable for archiving
The newest version!
/*
This file is part of the iText (R) project.
Copyright (c) 1998-2024 Apryse Group NV
Authors: Apryse 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.image.ImageType;
import com.itextpdf.io.image.ImageTypeDetector;
import com.itextpdf.io.image.TiffImageData;
import com.itextpdf.io.util.UrlUtil;
import com.itextpdf.io.source.RandomAccessFileOrArray;
import com.itextpdf.io.source.RandomAccessSourceFactory;
import com.itextpdf.commons.utils.MessageFormatUtil;
import com.itextpdf.pdfocr.tesseract4.exceptions.PdfOcrTesseract4Exception;
import com.itextpdf.pdfocr.tesseract4.exceptions.PdfOcrTesseract4ExceptionMessageConstant;
import com.itextpdf.pdfocr.tesseract4.exceptions.PdfOcrInputTesseract4Exception;
import com.itextpdf.pdfocr.tesseract4.logs.Tesseract4LogMessageConstant;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import javax.imageio.ImageIO;
import net.sourceforge.lept4j.Pix;
import org.slf4j.LoggerFactory;
/**
* Utilities class to work with images.
* Class provides tools for basic image preprocessing.
*/
class ImagePreprocessingUtil {
/**
* Creates a new {@link ImagePreprocessingUtil} instance.
*/
private ImagePreprocessingUtil() {
}
/**
* Counts number of pages in the provided tiff image.
*
* @param inputImage input image {@link java.io.File}
* @return number of pages in the provided TIFF image
* @throws IOException if error occurred during creating a
* {@link com.itextpdf.io.source.IRandomAccessSource} based on a filename
* string
*/
static int getNumberOfPageTiff(final File inputImage)
throws IOException {
RandomAccessFileOrArray raf = new RandomAccessFileOrArray(
new RandomAccessSourceFactory()
.createBestSource(
inputImage.getAbsolutePath()));
int numOfPages = TiffImageData.getNumberOfPages(raf);
raf.close();
return numOfPages;
}
/**
* Checks whether image format is TIFF.
*
* @param inputImage input image {@link java.io.File}
* @return true if provided image has 'tiff' or 'tif' extension
*/
static boolean isTiffImage(final File inputImage) {
return getImageType(inputImage) == ImageType.TIFF;
}
/**
* Gets the image type.
*
* @param inputImage input image {@link java.io.File}
* @return image type {@link com.itextpdf.io.image.ImageType}
*/
static ImageType getImageType(final File inputImage) {
ImageType type;
try {
type = ImageTypeDetector.detectImageType(UrlUtil.toURL(inputImage.getAbsolutePath()));
} catch (Exception e) {
LoggerFactory.getLogger(ImagePreprocessingUtil.class).error(MessageFormatUtil
.format(Tesseract4LogMessageConstant
.CANNOT_READ_INPUT_IMAGE,
e.getMessage()));
throw new PdfOcrInputTesseract4Exception(
PdfOcrTesseract4ExceptionMessageConstant.CANNOT_READ_PROVIDED_IMAGE)
.setMessageParams(inputImage.getAbsolutePath());
}
return type;
}
/**
* Reads provided image file using stream.
*
* @param inputFile input image {@link java.io.File}
* @return returns a {@link java.awt.image.BufferedImage} as the result
* @throws IllegalArgumentException if error occurred during reading a file
* @throws IOException if error occurred during reading a file
*/
static BufferedImage readImageFromFile(final File inputFile)
throws IllegalArgumentException, IOException {
FileInputStream is = new FileInputStream(inputFile.getAbsolutePath());
BufferedImage bi = ImageIO.read(is);
is.close();
return bi;
}
/**
* Reads input file as Leptonica {@link net.sourceforge.lept4j.Pix} and
* converts it to {@link java.awt.image.BufferedImage}.
*
* @param inputImage input image {@link java.io.File}
* @return returns a {@link java.awt.image.BufferedImage} as the result
* @throws IOException is error occurred during conversion from
* {@link net.sourceforge.lept4j.Pix} to
* {@link java.awt.image.BufferedImage}
*/
static BufferedImage readAsPixAndConvertToBufferedImage(
final File inputImage)
throws IOException {
Pix pix = TesseractOcrUtil.readPixFromFile(inputImage);
return TesseractOcrUtil.convertPixToImage(pix);
}
/**
* Performs basic image preprocessing using buffered image (if provided).
* Preprocessed image will be saved in temporary directory.
*
* @param inputFile input image {@link File}
* @param pageNumber number of page to be preprocessed
* @param imagePreprocessingOptions {@link ImagePreprocessingOptions}
* @return created preprocessed image as {@link net.sourceforge.lept4j.Pix}
* @throws PdfOcrTesseract4Exception if it was not possible to read or convert
* input file
*/
static Pix preprocessImage(final File inputFile,
final int pageNumber,
final ImagePreprocessingOptions imagePreprocessingOptions)
throws PdfOcrTesseract4Exception {
Pix pix = null;
// read image
if (isTiffImage(inputFile)) {
pix = TesseractOcrUtil.readPixPageFromTiff(inputFile,
pageNumber - 1);
} else {
pix = TesseractOcrUtil.readPix(inputFile);
}
if (pix == null) {
throw new PdfOcrInputTesseract4Exception(
PdfOcrTesseract4ExceptionMessageConstant.CANNOT_READ_PROVIDED_IMAGE)
.setMessageParams(inputFile.getAbsolutePath());
}
return TesseractOcrUtil.preprocessPix(pix, imagePreprocessingOptions);
}
/**
* Reads input image as a {@link java.awt.image.BufferedImage}.
* If it is not possible to read {@link java.awt.image.BufferedImage} from
* input file, image will be read as a {@link net.sourceforge.lept4j.Pix}
* and then converted to {@link java.awt.image.BufferedImage}.
* @param inputImage original input image
* @return input image as a {@link java.awt.image.BufferedImage}
*/
static BufferedImage readImage(File inputImage) {
BufferedImage bufferedImage = null;
try {
bufferedImage = ImagePreprocessingUtil
.readAsPixAndConvertToBufferedImage(
inputImage);
} catch (IllegalArgumentException | IOException ex) {
LoggerFactory.getLogger(ImagePreprocessingUtil.class)
.info(MessageFormatUtil.format(
Tesseract4LogMessageConstant
.CANNOT_READ_INPUT_IMAGE,
ex.getMessage()));
}
if (bufferedImage == null) {
try {
bufferedImage = ImagePreprocessingUtil
.readImageFromFile(inputImage);
} catch (IllegalArgumentException | IOException ex) {
LoggerFactory.getLogger(ImagePreprocessingUtil.class).info(
MessageFormatUtil.format(
Tesseract4LogMessageConstant
.CANNOT_CREATE_BUFFERED_IMAGE,
ex.getMessage()));
}
}
return bufferedImage;
}
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy