Java: Insert Image Watermarks to PDF

A PDF image watermark is a semi-transparent picture integrated into a PDF page as a fixed element. It is often used to protect the copyright and other rights of the document owner since it can't be removed easily. What's more, for famous PDF publishers, image watermarks are also used to increase the credibility of their documents. With an image watermark of their logo, the readers of documents can identify them at a glance. This article will show how to insert image watermarks into PDF documents using Spire.PDF for Java with simple code.

Install Spire.PDF for Java

First of all, you're required to add the Spire.Pdf.jar file as a dependency in your Java program. The JAR file can be downloaded from this link. If you use Maven, you can easily import the JAR file in your application by adding the following code to your project's pom.xml file.

<repositories>
    <repository>
        <id>com.e-iceblue</id>
        <name>e-iceblue</name>
        <url>https://repo.e-iceblue.com/nexus/content/groups/public/</url>
    </repository>
</repositories>
<dependencies>
    <dependency>
        <groupId>e-iceblue</groupId>
        <artifactId>spire.pdf</artifactId>
        <version>10.10.0</version>
    </dependency>
</dependencies>
    

Insert a Single Picture Watermark into PDF

A single image watermark is usually placed at the center of a PDF page. The detailed steps for inserting a single image watermark are as follows.

  • Create a PdfDocument class instance.
  • Load a PDF document using PdfDocument.loadFromFile() method.
  • Load a picture using PdfImage.fromFile() method.
  • Get the width and height of the picture using PdfImage.getWidth() and PdfImage.getHeight() methods.
  • Loop through the pages in the PDF document to insert watermarks
  • Get a page using PdfDocument.getPages().get() method.
  • Get the width and height of the page using PdfPageBase.getActualSize().getWidth() and PdfPageBase.getActualSize().getHeight() methods.
  • Set the transparency of the watermark picture using PdfPageBase.getCanvas().setTransparency() method.
  • Draw the watermark picture at the center of the page using PdfPageBase.getCanvas().drawImage() method.
  • Save the document using PdfDocument.saveToFile() method.
  • Java
import com.spire.pdf.PdfDocument;
import com.spire.pdf.PdfPageBase;
import com.spire.pdf.graphics.PdfBrush;
import com.spire.pdf.graphics.PdfImage;

import java.awt.*;
import java.awt.image.BufferedImage;

public class insertSingleImageWatermark {
    public static void main(String[] args) {

        //Create a PdfDocument class instance
        PdfDocument pdf = new PdfDocument();

        //Load a PDF file
        pdf.loadFromFile("Goodbye Pixel.pdf");

        //Load a picture
        PdfImage image = PdfImage.fromFile("Logo.png");

        //Get the width and height of the image
        int imageWidth = image.getWidth();
        int imageHeight = image.getHeight();

        //Loop through the pages to insert watermark
        for (int i = 0; i < pdf.getPages().getCount(); i++) {
            //Get a page
            PdfPageBase page = pdf.getPages().get(i);
            //Get the width and height of the page
            float pageWidth = (float) (page.getActualSize().getWidth());
            float pageHeight = (float) (page.getActualSize().getHeight());
            //Set the transparency of the watermark
            page.getCanvas().setTransparency(0.3f);
            //Draw the watermark picture at the middle of the page
            page.getCanvas().drawImage(image, pageWidth/2 - imageWidth/2, pageHeight/2 - imageHeight/2, imageWidth, imageHeight);
        }

        //Save the file
        pdf.saveToFile("SingleImageWatermark.pdf");
    }
}

Java: Insert Image Watermarks to PDF

Insert Tiled Picture Watermarks into PDF

Tiled image watermarks contain a picture that is displayed multiple times on one PDF page. When inserting a tiled image watermark, we can set the number of repetitions of its picture. The detailed steps for inserting a tiled image watermark are as follow.

  • Create a PdfDocument class instance.
  • Load a PDF document using PdfDocument.loadFromFile() method.
  • Load a picture using PdfImage.fromFile() method.
  • Loop through the pages to insert watermarks.
  • Get a specific page using PdfDocument.getPages().get() method.
  • Use the custom method insertImageWatermark() to insert a tiled image watermark.
  • Save the document using PdfDocument.saveToFile() method.
  • Java
import com.spire.pdf.PdfDocument;
import com.spire.pdf.PdfPageBase;
import com.spire.pdf.graphics.PdfBrush;
import com.spire.pdf.graphics.PdfImage;
import com.spire.pdf.graphics.PdfTilingBrush;

import java.awt.*;

public class insertTiledImageWatermark {
    public static void main(String[] args) {
        //Create a PdfDocument class instance
        PdfDocument pdf = new PdfDocument();

        //Load a PDF file
        pdf.loadFromFile("Goodbye Pixel.pdf");

        //Load a picture
        PdfImage image = PdfImage.fromFile("Logo.png");

        //Loop through the pages in the PDF document to insert watermark
        for (int i = 0; i < pdf.getPages().getCount(); i++ ) {
            //Get a Page
            PdfPageBase page = pdf.getPages().get(i);
            //Use the custom method to insert a tiled image watermark
            insertImageWatermark(page, image, 3, 3);
        }

        //Save the file
        pdf.saveToFile("TiledImageWatermark.pdf");
    }
    static void insertImageWatermark(PdfPageBase page, PdfImage image, int row, int column) {
        //Create a tile brush
        PdfTilingBrush brush = new PdfTilingBrush(new Dimension((int) (page.getActualSize().getWidth()/column), (int) (page.getActualSize().getHeight()/row)));
        brush.getGraphics().setTransparency(0.3f);
        brush.getGraphics().save();
        brush.getGraphics().translateTransform(brush.getSize().getWidth()/2 - image.getWidth()/2, brush.getSize().getHeight()/2 - image.getHeight()/2);
        //Draw the watermark image at the center of the page
        brush.getGraphics().drawImage(image, 0, 0);
        brush.getGraphics().restore();
        //Use the tile brush to draw the watermark picture
        page.getCanvas().drawRectangle(brush, new Rectangle(new Point(0, 0), new Dimension((int) (page.getActualSize().getWidth()), (int) (page.getActualSize().getHeight()))));
    }
}

Java: Insert Image Watermarks to PDF

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