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257 lines
8.3 KiB
Java
257 lines
8.3 KiB
Java
/**
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* Copyright @ 2012 Quan Nguyen
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may not
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* use this file except in compliance with the License. You may obtain a copy of
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* the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations under
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* the License.
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*/
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package com.sismics.tess4j;
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import java.awt.Rectangle;
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import java.awt.image.BufferedImage;
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import java.awt.image.RenderedImage;
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import java.io.IOException;
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import java.nio.ByteBuffer;
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import java.util.ArrayList;
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import java.util.Enumeration;
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import java.util.List;
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import java.util.Properties;
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import javax.imageio.IIOImage;
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import com.sun.jna.Pointer;
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/**
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* An object layer on top of
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* <code>TessAPI</code>, provides character recognition support for common image
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* formats, and multi-page TIFF images beyond the uncompressed, binary TIFF
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* format supported by Tesseract OCR engine. The extended capabilities are
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* provided by the
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* <code>Java Advanced Imaging Image I/O Tools</code>. <br /><br /> Support for
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* PDF documents is available through
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* <code>Ghost4J</code>, a
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* <code>JNA</code> wrapper for
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* <code>GPL Ghostscript</code>, which should be installed and included in
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* system path. <br /><br /> Any program that uses the library will need to
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* ensure that the required libraries (the
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* <code>.jar</code> files for
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* <code>jna</code>,
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* <code>jai-imageio</code>, and
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* <code>ghost4j</code>) are in its compile and run-time
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* <code>classpath</code>.
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*/
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public class Tesseract {
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private static Tesseract instance;
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private final static Rectangle EMPTY_RECTANGLE = new Rectangle();
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private String language = "eng";
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private String datapath = null;
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private int psm = TessAPI.TessPageSegMode.PSM_AUTO;
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private boolean hocr;
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private int pageNum;
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private int ocrEngineMode = TessAPI.TessOcrEngineMode.OEM_DEFAULT;
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private Properties prop = new Properties();
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public final static String htmlBeginTag =
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"<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\""
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+ " \"http://www.w3.org/TR/html4/loose.dtd\">\n"
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+ "<html>\n<head>\n<title></title>\n"
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+ "<meta http-equiv=\"Content-Type\" content=\"text/html;"
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+ "charset=utf-8\" />\n<meta name='ocr-system' content='tesseract'/>\n"
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+ "</head>\n<body>\n";
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public final static String htmlEndTag = "</body>\n</html>\n";
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/**
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* Private constructor.
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*/
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private Tesseract() {
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System.setProperty("jna.encoding", "UTF8");
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}
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/**
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* Gets an instance of the class library.
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*
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* @return instance
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*/
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public static synchronized Tesseract getInstance() {
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if (instance == null) {
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instance = new Tesseract();
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}
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return instance;
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}
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/**
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* Sets tessdata path.
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*
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* @param datapath the tessdata path to set
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*/
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public void setDatapath(String datapath) {
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this.datapath = datapath;
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}
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/**
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* Sets language for OCR.
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*
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* @param language the language code, which follows ISO 639-3 standard.
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*/
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public void setLanguage(String language) {
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this.language = language;
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}
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/**
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* Sets OCR engine mode.
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*
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* @param ocrEngineMode the OcrEngineMode to set
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*/
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public void setOcrEngineMode(int ocrEngineMode) {
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this.ocrEngineMode = ocrEngineMode;
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}
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/**
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* Sets page segmentation mode.
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*
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* @param mode the page segmentation mode to set
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*/
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public void setPageSegMode(int mode) {
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this.psm = mode;
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}
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/**
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* Enables hocr output.
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*
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* @param hocr to enable or disable hocr output
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*/
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public void setHocr(boolean hocr) {
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this.hocr = hocr;
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prop.setProperty("tessedit_create_hocr", hocr ? "1" : "0");
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}
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/**
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* Set the value of Tesseract's internal parameter.
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*
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* @param key variable name, e.g.,
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* <code>tessedit_create_hocr</code>,
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* <code>tessedit_char_whitelist</code>, etc.
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* @param value value for corresponding variable, e.g., "1", "0",
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* "0123456789", etc.
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*/
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public void setTessVariable(String key, String value) {
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prop.setProperty(key, value);
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}
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/**
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* Performs OCR operation.
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*
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* @param bi a buffered image
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* @return the recognized text
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* @throws TesseractException
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*/
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public String doOCR(BufferedImage bi) throws TesseractException {
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return doOCR(bi, null);
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}
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/**
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* Performs OCR operation.
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*
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* @param bi a buffered image
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* @param rect the bounding rectangle defines the region of the image to be
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* recognized. A rectangle of zero dimension or
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* <code>null</code> indicates the whole image.
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* @return the recognized text
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* @throws TesseractException
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*/
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public String doOCR(BufferedImage bi, Rectangle rect) throws TesseractException {
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IIOImage oimage = new IIOImage(bi, null, null);
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List<IIOImage> imageList = new ArrayList<IIOImage>();
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imageList.add(oimage);
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return doOCR(imageList, rect);
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}
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/**
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* Performs OCR operation.
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*
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* @param imageList a list of
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* <code>IIOImage</code> objects
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* @param rect the bounding rectangle defines the region of the image to be
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* recognized. A rectangle of zero dimension or
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* <code>null</code> indicates the whole image.
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* @return the recognized text
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* @throws TesseractException
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*/
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public String doOCR(List<IIOImage> imageList, Rectangle rect) throws TesseractException {
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StringBuilder sb = new StringBuilder();
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pageNum = 0;
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for (IIOImage oimage : imageList) {
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pageNum++;
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try {
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ByteBuffer buf = ImageIOHelper.getImageByteBuffer(oimage);
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RenderedImage ri = oimage.getRenderedImage();
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String pageText = doOCR(ri.getWidth(), ri.getHeight(), buf, rect, ri.getColorModel().getPixelSize());
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sb.append(pageText);
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} catch (IOException ioe) {
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//skip the problematic image
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System.err.println(ioe.getMessage());
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}
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}
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if (hocr) {
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sb.insert(0, htmlBeginTag).append(htmlEndTag);
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}
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return sb.toString();
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}
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/**
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* Performs OCR operation. Use
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* <code>SetImage</code>, (optionally)
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* <code>SetRectangle</code>, and one or more of the
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* <code>Get*Text</code> functions.
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*
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* @param xsize width of image
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* @param ysize height of image
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* @param buf pixel data
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* @param rect the bounding rectangle defines the region of the image to be
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* recognized. A rectangle of zero dimension or
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* <code>null</code> indicates the whole image.
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* @param bpp bits per pixel, represents the bit depth of the image, with 1
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* for binary bitmap, 8 for gray, and 24 for color RGB.
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* @return the recognized text
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* @throws TesseractException
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*/
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public String doOCR(int xsize, int ysize, ByteBuffer buf, Rectangle rect, int bpp) throws TesseractException {
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TessAPI api = TessAPI.INSTANCE;
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TessAPI.TessBaseAPI handle = api.TessBaseAPICreate();
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api.TessBaseAPIInit2(handle, datapath, language, ocrEngineMode);
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api.TessBaseAPISetPageSegMode(handle, psm);
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Enumeration<?> em = prop.propertyNames();
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while (em.hasMoreElements()) {
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String key = (String) em.nextElement();
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api.TessBaseAPISetVariable(handle, key, prop.getProperty(key));
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}
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int bytespp = bpp / 8;
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int bytespl = (int) Math.ceil(xsize * bpp / 8.0);
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api.TessBaseAPISetImage(handle, buf, xsize, ysize, bytespp, bytespl);
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if (rect != null && !rect.equals(EMPTY_RECTANGLE)) {
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api.TessBaseAPISetRectangle(handle, rect.x, rect.y, rect.width, rect.height);
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}
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Pointer utf8Text = hocr ? api.TessBaseAPIGetHOCRText(handle, pageNum - 1) : api.TessBaseAPIGetUTF8Text(handle);
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String str = utf8Text.getString(0);
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api.TessDeleteText(utf8Text);
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api.TessBaseAPIDelete(handle);
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return str;
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}
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}
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