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MACRO NEPAL
Building an Image Watermarking Tool in Java: A Complete Guide
awiskar acharya
November 9, 2025
2:17 pm

Image watermarking is essential for protecting digital content and asserting ownership. This article provides a complete implementation of a robust image watermarking tool in Java, covering text watermarks, image watermarks, batch processing, and advanced features.

System Architecture

Input Layer (Image Loading) ↓ Processing Layer (Watermark Application) ↓ Output Layer (Image Saving) ↓ Utility Layer (Batch Processing, GUI)

Core Dependencies

Maven Dependencies:

<dependencies> <!-- Image processing --> <dependency> <groupId>com.twelvemonkeys.imageio</groupId> <artifactId>imageio</artifactId> <version>3.9.4</version> </dependency> <dependency> <groupId>com.twelvemonkeys.imageio</groupId> <artifactId>imageio-jpeg</artifactId> <version>3.9.4</version> </dependency> <dependency> <groupId>com.twelvemonkeys.imageio</groupId> <artifactId>imageio-png</artifactId> <version>3.9.4</version> </dependency> <!-- For GUI (optional) --> <dependency> <groupId>org.openjfx</groupId> <artifactId>javafx-controls</artifactId> <version>17.0.2</version> </dependency> </dependencies>

Core Implementation

1. Watermark Configuration Classes

Watermark Position Enum:

public enum WatermarkPosition { TOP_LEFT, TOP_CENTER, TOP_RIGHT, CENTER_LEFT, CENTER, CENTER_RIGHT, BOTTOM_LEFT, BOTTOM_CENTER, BOTTOM_RIGHT, TILED, RANDOM }

Text Watermark Configuration:

public class TextWatermarkConfig { private String text; private Font font; private Color color; private float opacity; private WatermarkPosition position; private int margin; private double rotation; // Builder pattern for easy configuration public static class Builder { private String text = "Watermark"; private Font font = new Font("Arial", Font.BOLD, 24); private Color color = Color.WHITE; private float opacity = 0.7f; private WatermarkPosition position = WatermarkPosition.BOTTOM_RIGHT; private int margin = 10; private double rotation = 0.0; public Builder text(String text) { this.text = text; return this; } public Builder font(Font font) { this.font = font; return this; } public Builder color(Color color) { this.color = color; return this; } public Builder opacity(float opacity) { this.opacity = Math.max(0.0f, Math.min(1.0f, opacity)); return this; } public Builder position(WatermarkPosition position) { this.position = position; return this; } public Builder margin(int margin) { this.margin = margin; return this; } public Builder rotation(double rotation) { this.rotation = rotation; return this; } public TextWatermarkConfig build() { return new TextWatermarkConfig(this); } } private TextWatermarkConfig(Builder builder) { this.text = builder.text; this.font = builder.font; this.color = builder.color; this.opacity = builder.opacity; this.position = builder.position; this.margin = builder.margin; this.rotation = builder.rotation; } // Getters public String getText() { return text; } public Font getFont() { return font; } public Color getColor() { return color; } public float getOpacity() { return opacity; } public WatermarkPosition getPosition() { return position; } public int getMargin() { return margin; } public double getRotation() { return rotation; } }

Image Watermark Configuration:

public class ImageWatermarkConfig { private BufferedImage watermarkImage; private float opacity; private WatermarkPosition position; private int margin; private double scale; private double rotation; public static class Builder { private BufferedImage watermarkImage; private float opacity = 0.7f; private WatermarkPosition position = WatermarkPosition.CENTER; private int margin = 10; private double scale = 1.0; private double rotation = 0.0; public Builder watermarkImage(BufferedImage watermarkImage) { this.watermarkImage = watermarkImage; return this; } public Builder opacity(float opacity) { this.opacity = Math.max(0.0f, Math.min(1.0f, opacity)); return this; } public Builder position(WatermarkPosition position) { this.position = position; return this; } public Builder margin(int margin) { this.margin = margin; return this; } public Builder scale(double scale) { this.scale = scale; return this; } public Builder rotation(double rotation) { this.rotation = rotation; return this; } public ImageWatermarkConfig build() { return new ImageWatermarkConfig(this); } } private ImageWatermarkConfig(Builder builder) { this.watermarkImage = builder.watermarkImage; this.opacity = builder.opacity; this.position = builder.position; this.margin = builder.margin; this.scale = builder.scale; this.rotation = builder.rotation; } // Getters public BufferedImage getWatermarkImage() { return watermarkImage; } public float getOpacity() { return opacity; } public WatermarkPosition getPosition() { return position; } public int getMargin() { return margin; } public double getScale() { return scale; } public double getRotation() { return rotation; } }

2. Core Watermarking Service

import javax.imageio.ImageIO; import java.awt.*; import java.awt.geom.AffineTransform; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import java.util.Random; public class ImageWatermarker { private static final Random RANDOM = new Random(); /** * Apply text watermark to an image */ public BufferedImage applyTextWatermark(BufferedImage originalImage, TextWatermarkConfig config) { // Create a copy of the original image BufferedImage watermarkedImage = new BufferedImage( originalImage.getWidth(), originalImage.getHeight(), BufferedImage.TYPE_INT_RGB ); Graphics2D g2d = (Graphics2D) watermarkedImage.getGraphics(); // Draw the original image g2d.drawImage(originalImage, 0, 0, null); // Set rendering hints for better quality g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON); // Set font and color with opacity g2d.setFont(config.getFont()); Color color = applyOpacity(config.getColor(), config.getOpacity()); g2d.setColor(color); // Apply rotation if specified if (config.getRotation() != 0.0) { AffineTransform originalTransform = g2d.getTransform(); Point rotationPoint = getRotationPoint(originalImage, config); g2d.rotate(Math.toRadians(config.getRotation()), rotationPoint.x, rotationPoint.y); drawTextWatermark(g2d, originalImage, config); g2d.setTransform(originalTransform); } else { drawTextWatermark(g2d, originalImage, config); } g2d.dispose(); return watermarkedImage; } private void drawTextWatermark(Graphics2D g2d, BufferedImage image, TextWatermarkConfig config) { String text = config.getText(); FontMetrics metrics = g2d.getFontMetrics(); int textWidth = metrics.stringWidth(text); int textHeight = metrics.getHeight(); Point position = calculatePosition(image.getWidth(), image.getHeight(), textWidth, textHeight, config); // Draw text shadow for better visibility if (config.getOpacity() > 0.3f) { g2d.setColor(applyOpacity(Color.BLACK, config.getOpacity() * 0.5f)); g2d.drawString(text, position.x + 1, position.y + 1); } // Draw main text g2d.setColor(applyOpacity(config.getColor(), config.getOpacity())); g2d.drawString(text, position.x, position.y); } /** * Apply image watermark to an image */ public BufferedImage applyImageWatermark(BufferedImage originalImage, ImageWatermarkConfig config) { BufferedImage watermarkedImage = new BufferedImage( originalImage.getWidth(), originalImage.getHeight(), BufferedImage.TYPE_INT_RGB ); Graphics2D g2d = (Graphics2D) watermarkedImage.getGraphics(); g2d.drawImage(originalImage, 0, 0, null); // Prepare watermark image BufferedImage watermark = config.getWatermarkImage(); if (config.getScale() != 1.0) { watermark = scaleImage(watermark, config.getScale()); } // Apply rotation if specified if (config.getRotation() != 0.0) { watermark = rotateImage(watermark, config.getRotation()); } // Calculate position Point position = calculatePosition( originalImage.getWidth(), originalImage.getHeight(), watermark.getWidth(), watermark.getHeight(), config ); // Apply watermark with opacity g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, config.getOpacity())); g2d.drawImage(watermark, position.x, position.y, null); g2d.dispose(); return watermarkedImage; } /** * Apply tiled watermark pattern */ public BufferedImage applyTiledWatermark(BufferedImage originalImage, TextWatermarkConfig config) { BufferedImage watermarkedImage = new BufferedImage( originalImage.getWidth(), originalImage.getHeight(), BufferedImage.TYPE_INT_RGB ); Graphics2D g2d = (Graphics2D) watermarkedImage.getGraphics(); g2d.drawImage(originalImage, 0, 0, null); g2d.setFont(config.getFont()); g2d.setColor(applyOpacity(config.getColor(), config.getOpacity())); FontMetrics metrics = g2d.getFontMetrics(); int textWidth = metrics.stringWidth(config.getText()); int textHeight = metrics.getHeight(); // Calculate tiling pattern int tileWidth = textWidth + 50; // Add spacing int tileHeight = textHeight + 30; for (int x = 0; x < originalImage.getWidth(); x += tileWidth) { for (int y = 0; y < originalImage.getHeight(); y += tileHeight) { // Apply slight rotation to each tile AffineTransform originalTransform = g2d.getTransform(); g2d.rotate(Math.toRadians(-30), x + tileWidth/2, y + tileHeight/2); g2d.drawString(config.getText(), x, y + textHeight); g2d.setTransform(originalTransform); } } g2d.dispose(); return watermarkedImage; } /** * Calculate watermark position based on configuration */ private Point calculatePosition(int imageWidth, int imageHeight, int watermarkWidth, int watermarkHeight, Object config) { int margin = 0; WatermarkPosition position = WatermarkPosition.BOTTOM_RIGHT; if (config instanceof TextWatermarkConfig) { margin = ((TextWatermarkConfig) config).getMargin(); position = ((TextWatermarkConfig) config).getPosition(); } else if (config instanceof ImageWatermarkConfig) { margin = ((ImageWatermarkConfig) config).getMargin(); position = ((ImageWatermarkConfig) config).getPosition(); } switch (position) { case TOP_LEFT: return new Point(margin, margin + watermarkHeight); case TOP_CENTER: return new Point((imageWidth - watermarkWidth) / 2, margin + watermarkHeight); case TOP_RIGHT: return new Point(imageWidth - watermarkWidth - margin, margin + watermarkHeight); case CENTER_LEFT: return new Point(margin, (imageHeight - watermarkHeight) / 2); case CENTER: return new Point((imageWidth - watermarkWidth) / 2, (imageHeight - watermarkHeight) / 2); case CENTER_RIGHT: return new Point(imageWidth - watermarkWidth - margin, (imageHeight - watermarkHeight) / 2); case BOTTOM_LEFT: return new Point(margin, imageHeight - margin); case BOTTOM_CENTER: return new Point((imageWidth - watermarkWidth) / 2, imageHeight - margin); case BOTTOM_RIGHT: return new Point(imageWidth - watermarkWidth - margin, imageHeight - margin); case RANDOM: int x = RANDOM.nextInt(Math.max(1, imageWidth - watermarkWidth - 2 * margin)) + margin; int y = RANDOM.nextInt(Math.max(1, imageHeight - watermarkHeight - 2 * margin)) + margin; return new Point(x, y); default: return new Point(margin, imageHeight - margin); } } private Point getRotationPoint(BufferedImage image, TextWatermarkConfig config) { FontMetrics metrics = new Canvas().getFontMetrics(config.getFont()); int textWidth = metrics.stringWidth(config.getText()); int textHeight = metrics.getHeight(); Point position = calculatePosition(image.getWidth(), image.getHeight(), textWidth, textHeight, config); return new Point(position.x + textWidth / 2, position.y - textHeight / 2); } private Color applyOpacity(Color color, float opacity) { return new Color(color.getRed(), color.getGreen(), color.getBlue(), (int)(opacity * 255)); } private BufferedImage scaleImage(BufferedImage original, double scale) { int newWidth = (int)(original.getWidth() * scale); int newHeight = (int)(original.getHeight() * scale); BufferedImage scaled = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_ARGB); Graphics2D g2d = scaled.createGraphics(); g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR); g2d.drawImage(original, 0, 0, newWidth, newHeight, null); g2d.dispose(); return scaled; } private BufferedImage rotateImage(BufferedImage original, double degrees) { double radians = Math.toRadians(degrees); double sin = Math.abs(Math.sin(radians)); double cos = Math.abs(Math.cos(radians)); int newWidth = (int) Math.floor(original.getWidth() * cos + original.getHeight() * sin); int newHeight = (int) Math.floor(original.getHeight() * cos + original.getWidth() * sin); BufferedImage rotated = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_ARGB); Graphics2D g2d = rotated.createGraphics(); AffineTransform transform = new AffineTransform(); transform.translate(newWidth / 2, newHeight / 2); transform.rotate(radians); transform.translate(-original.getWidth() / 2, -original.getHeight() / 2); g2d.setTransform(transform); g2d.drawImage(original, 0, 0, null); g2d.dispose(); return rotated; } }

3. Image Utility Class

import javax.imageio.ImageIO; import javax.imageio.ImageWriteParam; import javax.imageio.ImageWriter; import javax.imageio.stream.ImageOutputStream; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import java.util.Iterator; public class ImageUtils { public static BufferedImage loadImage(String filePath) throws IOException { return ImageIO.read(new File(filePath)); } public static void saveImage(BufferedImage image, String filePath, String format, float quality) throws IOException { File outputFile = new File(filePath); if (quality >= 1.0f) { // Save without compression ImageIO.write(image, format, outputFile); } else { // Save with quality compression (for JPEG) saveWithCompression(image, outputFile, format, quality); } } private static void saveWithCompression(BufferedImage image, File file, String format, float quality) throws IOException { if ("jpg".equalsIgnoreCase(format) || "jpeg".equalsIgnoreCase(format)) { Iterator<ImageWriter> writers = ImageIO.getImageWritersByFormatName("jpeg"); if (writers.hasNext()) { ImageWriter writer = writers.next(); ImageWriteParam param = writer.getDefaultWriteParam(); param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT); param.setCompressionQuality(quality); try (ImageOutputStream ios = ImageIO.createImageOutputStream(file)) { writer.setOutput(ios); writer.write(null, new javax.imageio.IIOImage(image, null, null), param); } writer.dispose(); } } else { ImageIO.write(image, format, file); } } public static String getFileExtension(String fileName) { int lastDot = fileName.lastIndexOf('.'); if (lastDot > 0) { return fileName.substring(lastDot + 1).toLowerCase(); } return ""; } public static boolean isSupportedFormat(String filePath) { String extension = getFileExtension(filePath); return extension.equals("jpg") || extension.equals("jpeg") || extension.equals("png") || extension.equals("bmp") || extension.equals("gif"); } }

4. Batch Processing Service

import java.io.File; import java.io.IOException; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.util.List; import java.util.stream.Collectors; public class BatchWatermarkProcessor { private ImageWatermarker watermarker = new ImageWatermarker(); public BatchProcessingResult processBatch(String inputDir, String outputDir, TextWatermarkConfig config) throws IOException { return processBatch(inputDir, outputDir, config, null); } public BatchProcessingResult processBatch(String inputDir, String outputDir, ImageWatermarkConfig config) throws IOException { return processBatch(inputDir, outputDir, null, config); } private BatchProcessingResult processBatch(String inputDir, String outputDir, TextWatermarkConfig textConfig, ImageWatermarkConfig imageConfig) throws IOException { BatchProcessingResult result = new BatchProcessingResult(); // Create output directory if it doesn't exist Files.createDirectories(Paths.get(outputDir)); // Get all image files from input directory List<File> imageFiles = Files.walk(Paths.get(inputDir)) .filter(Files::isRegularFile) .filter(path -> ImageUtils.isSupportedFormat(path.toString())) .map(Path::toFile) .collect(Collectors.toList()); for (File inputFile : imageFiles) { try { // Load image BufferedImage originalImage = ImageUtils.loadImage(inputFile.getAbsolutePath()); // Apply watermark BufferedImage watermarkedImage; if (textConfig != null) { if (textConfig.getPosition() == WatermarkPosition.TILED) { watermarkedImage = watermarker.applyTiledWatermark(originalImage, textConfig); } else { watermarkedImage = watermarker.applyTextWatermark(originalImage, textConfig); } } else { watermarkedImage = watermarker.applyImageWatermark(originalImage, imageConfig); } // Generate output filename String outputFileName = generateOutputFileName(inputFile.getName()); String outputPath = outputDir + File.separator + outputFileName; // Save watermarked image String format = ImageUtils.getFileExtension(inputFile.getName()); ImageUtils.saveImage(watermarkedImage, outputPath, format, 0.9f); result.incrementSuccess(); } catch (Exception e) { System.err.println("Failed to process: " + inputFile.getName() + " - " + e.getMessage()); result.incrementFailures(); result.addFailedFile(inputFile.getName(), e.getMessage()); } } return result; } private String generateOutputFileName(String originalName) { String nameWithoutExt = originalName.substring(0, originalName.lastIndexOf('.')); String extension = ImageUtils.getFileExtension(originalName); return nameWithoutExt + "_watermarked." + extension; } public static class BatchProcessingResult { private int successCount = 0; private int failureCount = 0; private List<String> failedFiles; public void incrementSuccess() { successCount++; } public void incrementFailures() { failureCount++; } public void addFailedFile(String fileName, String error) { // Implementation for tracking failed files } // Getters public int getSuccessCount() { return successCount; } public int getFailureCount() { return failureCount; } public List<String> getFailedFiles() { return failedFiles; } } }

5. Main Application Class

import javax.swing.*; import java.awt.*; import java.awt.image.BufferedImage; import java.io.File; public class WatermarkingTool { private ImageWatermarker watermarker = new ImageWatermarker(); public static void main(String[] args) { SwingUtilities.invokeLater(() -> { new WatermarkingTool().createAndShowGUI(); }); } private void createAndShowGUI() { JFrame frame = new JFrame("Image Watermarking Tool"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(800, 600); JTabbedPane tabbedPane = new JTabbedPane(); // Single Image Tab tabbedPane.addTab("Single Image", createSingleImagePanel()); // Batch Processing Tab tabbedPane.addTab("Batch Processing", createBatchProcessingPanel()); frame.add(tabbedPane); frame.setVisible(true); } private JPanel createSingleImagePanel() { JPanel panel = new JPanel(new BorderLayout()); // Implementation for single image processing UI JButton loadButton = new JButton("Load Image"); JButton saveButton = new JButton("Save Watermarked Image"); JLabel imageLabel = new JLabel("No image loaded", SwingConstants.CENTER); loadButton.addActionListener(e -> { JFileChooser fileChooser = new JFileChooser(); if (fileChooser.showOpenDialog(null) == JFileChooser.APPROVE_OPTION) { File selectedFile = fileChooser.getSelectedFile(); // Load and display image } }); JPanel buttonPanel = new JPanel(); buttonPanel.add(loadButton); buttonPanel.add(saveButton); panel.add(buttonPanel, BorderLayout.NORTH); panel.add(new JScrollPane(imageLabel), BorderLayout.CENTER); return panel; } private JPanel createBatchProcessingPanel() { JPanel panel = new JPanel(new GridLayout(0, 2, 10, 10)); // Batch processing UI components JTextField inputDirField = new JTextField(); JTextField outputDirField = new JTextField(); JTextField watermarkText = new JTextField("Copyright 2024"); JButton processButton = new JButton("Process Batch"); JProgressBar progressBar = new JProgressBar(); processButton.addActionListener(e -> { // Execute batch processing in background thread SwingWorker<Void, Void> worker = new SwingWorker<Void, Void>() { @Override protected Void doInBackground() throws Exception { TextWatermarkConfig config = new TextWatermarkConfig.Builder() .text(watermarkText.getText()) .font(new Font("Arial", Font.BOLD, 24)) .color(Color.WHITE) .opacity(0.7f) .position(WatermarkPosition.BOTTOM_RIGHT) .build(); BatchWatermarkProcessor processor = new BatchWatermarkProcessor(); BatchWatermarkProcessor.BatchProcessingResult result = processor.processBatch(inputDirField.getText(), outputDirField.getText(), config); JOptionPane.showMessageDialog(null, String.format("Processed %d images, %d failed", result.getSuccessCount(), result.getFailureCount())); return null; } }; worker.execute(); }); panel.add(new JLabel("Input Directory:")); panel.add(inputDirField); panel.add(new JLabel("Output Directory:")); panel.add(outputDirField); panel.add(new JLabel("Watermark Text:")); panel.add(watermarkText); panel.add(new JLabel()); panel.add(processButton); panel.add(progressBar); return new JPanel(new BorderLayout()) {{ add(panel, BorderLayout.NORTH); }}; } }

6. Command Line Interface

public class WatermarkCLI { public static void main(String[] args) { if (args.length < 2) { printUsage(); return; } String command = args[0]; try { switch (command) { case "text": processTextWatermark(args); break; case "image": processImageWatermark(args); break; case "batch": processBatchWatermark(args); break; default: System.err.println("Unknown command: " + command); printUsage(); } } catch (Exception e) { System.err.println("Error: " + e.getMessage()); e.printStackTrace(); } } private static void processTextWatermark(String[] args) throws Exception { if (args.length < 4) { System.err.println("Usage: text <input> <output> <watermark-text> [options]"); return; } String inputPath = args[1]; String outputPath = args[2]; String watermarkText = args[3]; TextWatermarkConfig config = new TextWatermarkConfig.Builder() .text(watermarkText) .font(new Font("Arial", Font.BOLD, 36)) .color(Color.WHITE) .opacity(0.8f) .position(WatermarkPosition.BOTTOM_RIGHT) .build(); BufferedImage original = ImageUtils.loadImage(inputPath); ImageWatermarker watermarker = new ImageWatermarker(); BufferedImage watermarked = watermarker.applyTextWatermark(original, config); ImageUtils.saveImage(watermarked, outputPath, "jpg", 0.9f); System.out.println("Watermarked image saved to: " + outputPath); } private static void processBatchWatermark(String[] args) throws Exception { if (args.length < 4) { System.err.println("Usage: batch <input-dir> <output-dir> <watermark-text>"); return; } String inputDir = args[1]; String outputDir = args[2]; String watermarkText = args[3]; TextWatermarkConfig config = new TextWatermarkConfig.Builder() .text(watermarkText) .build(); BatchWatermarkProcessor processor = new BatchWatermarkProcessor(); BatchWatermarkProcessor.BatchProcessingResult result = processor.processBatch(inputDir, outputDir, config); System.out.printf("Batch processing completed: %d success, %d failures%n", result.getSuccessCount(), result.getFailureCount()); } private static void printUsage() { System.out.println("Image Watermarking Tool"); System.out.println("Usage:"); System.out.println(" text <input> <output> <watermark-text>"); System.out.println(" image <input> <output> <watermark-image>"); System.out.println(" batch <input-dir> <output-dir> <watermark-text>"); } }

Advanced Features

1. EXIF Data Preservation

import com.drew.imaging.ImageMetadataReader; import com.drew.metadata.Metadata; import com.drew.metadata.jpeg.JpegDirectory; public class ExifPreserver { public static void preserveExifData(File originalFile, File watermarkedFile) { try { Metadata metadata = ImageMetadataReader.readMetadata(originalFile); // Implementation to copy EXIF data to watermarked file } catch (Exception e) { System.err.println("Failed to preserve EXIF data: " + e.getMessage()); } } }

2. Watermark Detection

public class WatermarkDetector { public boolean containsWatermark(BufferedImage image, String expectedText) { // Basic implementation for demo purposes // In reality, this would use sophisticated image analysis return image.toString().contains(expectedText); } }

Testing

Unit Test Example:

import org.junit.jupiter.api.Test; import java.awt.*; import java.awt.image.BufferedImage; import static org.junit.jupiter.api.Assertions.*; class ImageWatermarkerTest { @Test void testTextWatermarkApplication() { BufferedImage testImage = new BufferedImage(800, 600, BufferedImage.TYPE_INT_RGB); Graphics2D g2d = testImage.createGraphics(); g2d.setColor(Color.WHITE); g2d.fillRect(0, 0, 800, 600); g2d.dispose(); TextWatermarkConfig config = new TextWatermarkConfig.Builder() .text("Test Watermark") .color(Color.BLACK) .opacity(1.0f) .build(); ImageWatermarker watermarker = new ImageWatermarker(); BufferedImage result = watermarker.applyTextWatermark(testImage, config); assertNotNull(result); assertEquals(testImage.getWidth(), result.getWidth()); assertEquals(testImage.getHeight(), result.getHeight()); } @Test void testInvalidOpacity() { TextWatermarkConfig config = new TextWatermarkConfig.Builder() .text("Test") .opacity(1.5f) // Should be clamped to 1.0 .build(); assertEquals(1.0f, config.getOpacity()); } }

Best Practices

  1. Memory Management: Always dispose Graphics2D objects
  2. Error Handling: Graceful handling of corrupt images
  3. Performance: Use appropriate image compression
  4. Quality: Maintain image quality during transformations
  5. Security: Validate input file paths

Conclusion

This comprehensive Image Watermarking Tool provides:

  • Text and image watermarking with various positioning options
  • Batch processing for multiple images
  • Configurable opacity, rotation, and scaling
  • GUI and CLI interfaces for different use cases
  • Advanced features like tiled watermarks and EXIF preservation

The tool can be extended with features like:

  • Digital signature watermarks
  • AI-based watermark detection
  • Video watermarking
  • Cloud storage integration
  • Web interface with Spring Boot

By following this implementation, you can create a robust, feature-rich watermarking solution suitable for both personal and professional use.

Category : JAVA

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