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The OcrConnectorBase class provides the interface to integrate any OCR solution into GroupDocs.Parser. An OCR connector is a subclass of OcrConnectorBase which overrides the following methods:
| Method | Description |
|---|---|
recognizeText(InputStream imageStream, OcrOptions options) | Extracts a text from the provided image stream. It is used when the getText(TextOptions) method of the Parser class is called with useOcr = true. |
recognizeTextAreas(InputStream imageStream, Size pageSize, OcrOptions options) | Extracts text areas from the provided image stream. It is used when the getTextAreas(PageTextAreaOptions) method of the Parser class is called with useOcr = true. |
recognizeText(InputStream imageStream, int pageIndex, OcrOptions options), recognizeTextAreas(InputStream imageStream, int pageIndex, Size pageSize, OcrOptions options) | The same methods with the zero-based index of the document page. |
The base implementation of these methods returns null. A connector must override the methods for the required functionality. In version 26.9 the parser calls the overloads without the pageIndex parameter, so override them (or make them call the overloads with pageIndex, as shown below).
| Parameter | Description |
|---|---|
imageStream | An image from which the text must be extracted. For a PDF document it’s the rendered page. |
pageIndex | A zero-based index of the page in the document (in the case when the image represents the document page). |
pageSize | A size of the image (in the case when the image represents the document page - the size of the page). |
options | Is used to define a rectangular area which restricts the area of the image and an OcrEventHandler object to handle warnings while the text recognition. |
OcrConnectorBase is a Java class, not an interface. The java module (node-java) can implement only Java interfaces in JavaScript (with java.newProxy); it can’t create a subclass of a Java class. That is why an OCR connector is a small Java class compiled into a JAR and added to the classpath of the Node.js application. The OCR engine is also a Java library in this case.
The following connector uses Aspose.OCR for Java on-premise API. It requires these Maven artifacts (download the JAR files from Maven Central or your Maven repository):
com.aspose:aspose-ocr:22.11(from the Aspose repositoryhttps://releases.aspose.com/java/repo/);com.microsoft.onnxruntime:onnxruntime:1.11.0(a dependency of Aspose.OCR).
package com.example;
import com.groupdocs.parser.data.Page;
import com.groupdocs.parser.data.PageTextArea;
import com.groupdocs.parser.data.Point;
import com.groupdocs.parser.data.Rectangle;
import com.groupdocs.parser.data.Size;
import com.groupdocs.parser.options.OcrConnectorBase;
import com.groupdocs.parser.options.OcrOptions;
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.InputStream;
import java.util.ArrayList;
/**
* OCR connector which uses Aspose.OCR for Java on-premise API.
*/
public class AsposeOcrOnPremise extends OcrConnectorBase {
@Override
public String recognizeText(InputStream imageStream, OcrOptions options) {
return recognizeText(imageStream, 0, options);
}
@Override
public String recognizeText(InputStream imageStream, int pageIndex, OcrOptions options) {
try {
com.aspose.ocr.RecognitionResult result = recognize(imageStream, pageIndex, options, false);
// Return a recognized text
return result.recognitionText;
} catch (Exception ex) {
return null;
}
}
@Override
public Iterable<PageTextArea> recognizeTextAreas(InputStream imageStream, Size pageSize, OcrOptions options) {
return recognizeTextAreas(imageStream, 0, pageSize, options);
}
@Override
public Iterable<PageTextArea> recognizeTextAreas(InputStream imageStream, int pageIndex, Size pageSize, OcrOptions options) {
try {
com.aspose.ocr.RecognitionResult result = recognize(imageStream, pageIndex, options, true);
// Create a page object; for images the page index is always zero
Page page = new Page(pageIndex, pageSize);
// Combine rectangle and text collections to produce PageTextArea collection
ArrayList<PageTextArea> areas = new ArrayList<>();
for (int i = 0; i < result.recognitionAreasRectangles.size(); i++) {
java.awt.Rectangle rect = result.recognitionAreasRectangles.get(i);
String text = result.recognitionAreasText.get(i);
areas.add(new PageTextArea(text, page, new Rectangle(
new Point(rect.getX(), rect.getY()), new Size(rect.getWidth(), rect.getHeight()))));
}
return areas;
} catch (Exception ex) {
return null;
}
}
private static com.aspose.ocr.RecognitionResult recognize(
InputStream imageStream, int pageIndex, OcrOptions options, boolean detectAreas) throws Exception {
// Create an instance of Aspose OCR API
com.aspose.ocr.AsposeOCR api = new com.aspose.ocr.AsposeOCR();
// Read the image from the stream
BufferedImage image = ImageIO.read(imageStream);
// Create an instance of RecognitionSettings
com.aspose.ocr.RecognitionSettings settings = new com.aspose.ocr.RecognitionSettings();
settings.setDetectAreas(detectAreas);
// Check if the rectangle is set
if (options != null && options.getRectangle() != null) {
Rectangle r = options.getRectangle();
ArrayList<java.awt.Rectangle> areas = new ArrayList<>();
areas.add(new java.awt.Rectangle(
(int) r.getLeft(), (int) r.getTop(),
(int) r.getSize().getWidth(), (int) r.getSize().getHeight()));
// Set recognition areas
settings.setRecognitionAreas(areas);
}
// Perform the text recognition
com.aspose.ocr.RecognitionResult result = api.RecognizePage(image, settings);
// Check if the handler is set
if (options != null && options.getHandler() != null) {
// Send all recognition warnings
options.getHandler().onWarnings(pageIndex, result.warnings);
}
return result;
}
}
Save the class as com/example/AsposeOcrOnPremise.java and compile it with the JDK. The classpath contains the JAR of the @groupdocs/groupdocs.parser package and the Aspose.OCR JAR (on Linux and macOS use : instead of ; as the classpath separator):
javac --release 8 -cp "node_modules/@groupdocs/groupdocs.parser/lib/groupdocs-parser-nodejs-26.9.jar;aspose-ocr-22.11.jar" -d out com/example/AsposeOcrOnPremise.java
jar cf ocr-connector.jar -C out .
Add the connector JAR and the OCR engine JARs to java.classpath before the first call to the package, then pass an instance of the connector to the ParserSettings constructor:
const path = require('path');
const java = require('java');
// Add the OCR connector and the OCR engine to the classpath before the JVM starts
java.classpath.push(path.join(__dirname, 'ocr-connector.jar'));
java.classpath.push(path.join(__dirname, 'aspose-ocr-22.11.jar'));
java.classpath.push(path.join(__dirname, 'onnxruntime-1.11.0.jar'));
const groupdocs = require('@groupdocs/groupdocs.parser');
const AsposeOcrOnPremise = java.import('com.example.AsposeOcrOnPremise');
// Create an instance of ParserSettings class with OCR Connector
const settings = new groupdocs.ParserSettings(new AsposeOcrOnPremise());
// Create an instance of Parser class with settings
const parser = new groupdocs.Parser('scan.pdf', settings);
try {
// Extract a text using OCR
const reader = parser.getText(new groupdocs.TextOptions(false, true));
if (reader === null) {
console.log("Text extraction isn't supported");
} else {
try {
console.log(reader.readToEnd());
} finally {
reader.close();
}
}
} finally {
parser.close();
}
process.exit(0);
Without a license Aspose.OCR works in the evaluation mode: it recognizes only a part of the image and adds a trial message to the text. To set the Aspose.OCR license, call the static method java.import('com.aspose.ocr.License').setLicense('Aspose.OCR.lic') before the recognition.
See OCR Usage Basics for more examples.
Along with the full-featured library we provide simple but powerful free Apps.
You are welcome to parse documents and extract data from PDF, DOC, DOCX, PPT, PPTX, XLS, XLSX, Emails and more with our Free Online Document Parser App.
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