How to create thumbnail Image using Java.

In this tutorial, I will show you how we can create thumbnail images using Java. Thumbnails are the reduced size of images or videos. Basically, if your website is loading a lot of images with larger pixel values i.e larger size then, the performance of the website will be poor. 

So, while loading web pages with images first showing thumbnails of images and when the user clicks on it then load the original images will increase the user experience and performance of the website.

Here, in order to do so, we are using the library called " thumbnailator" which will help to generate high-quality thumbnails.

Add Dependency:

Download the jar file from here. Load the downloaded jar file on your project.

For IntelliJ Idea:

Go to: File >> Project Structure(Ctr + Alt + Shift + s) >> Libraries  and click the + icon on the top left corner and select library file that we downloaded. Apply and save, now we are ready to write code. If you are using in an existing project like Gradle or Maven:

For Gradle:

Inside build.gradle file under dependencies, 

compile 'net.coobird:thumbnailator:0.4.8'

For Maven:

Inside pom.xml

<dependency>
  <groupid>net.coobird</groupid>
  <artifactid>thumbnailator</artifactid>
  <version>0.4.8</version>
</dependency>

Create thumbnail from image file:

Let's create a class called Thumbnail.java:

import net.coobird.thumbnailator.Thumbnails;
import java.io.File;
import java.io.IOException;

    public class Thumbnail {

    public static void main(String[] args) {
        String inputImagePath = "E:/image.jpg"; //input image path
        File inputFile = new File(inputImagePath);
        String fileName = inputFile.getName();
        String outputPath = "E:" + "/T_"+fileName; //output path to write thumbnail image
        Thumbnail.createFromImageFile(inputFile, outputPath);
    }

    private static void createFromImageFile(File inputFile, String outputPath){
        try {
            Thumbnails.of(inputFile)
                    .size(500, 500)
                    .toFile(outputPath);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Here, the image is resized to the square of size 500*500 i.e width*height.

Create thumbnail from Buffered image:

private static void createFromBufferedImage(BufferedImage image, String outputPath){
        try {
            Thumbnails.of(image)
                    .size(500, 500)
                    .toFile(outputPath);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

Create thumbnail Image by scaling:

private static void createByScaling(File inputFile, String outputPath){
        try {
            Thumbnails.of(inputFile)
                    .scale(0.25)
                    .toFile(outputPath);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

Here, it creates a thumbnail that is 25% of the original image.

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