Working with Images in Java: Libraries and Examples |…

Working with Images in Java: Libraries, Tools, and Code Examples

Java provides powerful built-in tools for working with graphics, as well as a rich ecosystem of third-party libraries. In this article, we will look at the main ways to load, process, transform, and save images in Java — from the standard javax.imageio and java.awt classes to popular libraries that simplify a developer's life.

1. Standard Tools: javax.imageio and java.awt.image

Basic work with raster images in Java is built on the javax.imageio package (loading/saving) and java.awt.image (working with pixels). The main class is BufferedImage, which stores the image in RAM.

Loading and Saving an Image

import javax.imageio.ImageIO;import java.awt.image.BufferedImage;import java.io.File;import java.io.IOException;

public class ImageExample {    public static void main(String[] args) throws IOException {        // Loading an image from a file        BufferedImage image = ImageIO.read(new File("input.jpg"));        System.out.println("Width: " + image.getWidth() + ", Height: " + image.getHeight());

        // Saving in a different format        ImageIO.write(image, "png", new File("output.png"));    }}

ImageIO supports formats: JPEG, PNG, BMP, WBMP, GIF (read only). To extend the list of formats, use ImageIO plugins (e.g., TwelveMonkeys).

Resizing (Manual Method)

import java.awt.Graphics2D;import java.awt.RenderingHints;import java.awt.image.BufferedImage;

public static BufferedImage resize(BufferedImage original, int newWidth, int newHeight) {    BufferedImage resized = new BufferedImage(newWidth, newHeight, original.getType());    Graphics2D g2d = resized.createGraphics();    g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);    g2d.drawImage(original, 0, 0, newWidth, newHeight, null);    g2d.dispose();    return resized;}

2. Java 2D API: Drawing and Filters

The Graphics2D class allows not only scaling but also applying effects, rotating, cropping images, adding text and geometric shapes.

Adding a Watermark

public static BufferedImage addWatermark(BufferedImage source, String text) {    BufferedImage result = new BufferedImage(source.getWidth(), source.getHeight(), source.getType());    Graphics2D g2d = result.createGraphics();    g2d.drawImage(source, 0, 0, null);    g2d.setColor(new Color(255, 255, 255, 128));    g2d.setFont(new Font("Arial", Font.BOLD, 40));    g2d.drawString(text, 20, source.getHeight() - 20);    g2d.dispose();    return result;}

Applying a Color Filter (Sepia)

public static BufferedImage applySepia(BufferedImage img) {    int width = img.getWidth();    int height = img.getHeight();    BufferedImage sepia = new BufferedImage(width, height, img.getType());

    for (int y = 0; y < height; y++) {        for (int x = 0; x < width; x++) {            int rgb = img.getRGB(x, y);            int r = (rgb >> 16) & 0xFF;            int g = (rgb >> 8) & 0xFF;            int b = rgb & 0xFF;

            int newR = (int) (0.393 * r + 0.769 * g + 0.189 * b);            int newG = (int) (0.349 * r + 0.686 * g + 0.168 * b);            int newB = (int) (0.272 * r + 0.534 * g + 0.131 * b);

            newR = Math.min(255, newR);            newG = Math.min(255, newG);            newB = Math.min(255, newB);

            int newPixel = (0xFF << 24) | (newR << 16) | (newG << 8) | newB;            sepia.setRGB(x, y, newPixel);        }    }    return sepia;}