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Java for Image Processing: 4 Libraries You Should Know

java for image processing

Image processing involves manipulating digital images using various algorithms to enhance their quality, extract useful information, and make them suitable for specific applications. This process can range from improving visual aesthetics to preparing images for machine learning algorithms.

In programming, image processing covers a broad spectrum of techniques, such as smoothing, sharpening, edge detection, and segmentation. These techniques, including computer vision, face recognition, and self-driving cars, are crucial in modern technologies.

Java, known for its powerful and flexible architecture, is well-suited for image processing tasks. It offers a robust set of APIs for handling and manipulating images. The Java Advanced Imaging (JAI) API provides high-performance image processing capabilities, while the Java2D API allows for advanced manipulation of 2D graphics and images.

However, working directly with Java’s image APIs can be challenging. Thankfully, specialized Java image processing libraries simplify the process significantly. In this article, we’ll review three open-source libraries that make Java image processing more accessible and a free option that enables advanced image processing with AI in just one line of code.

This is part of a series of articles about image optimization

In this article:

BoofCV for Java Image Processing

BoofCV is a comprehensive library designed for real-time computer vision and image processing applications. It focuses on providing simple and efficient algorithms for tasks such as image enhancement, feature detection, and object tracking.

Written in pure Java, the library is suitable for both desktop and mobile applications. BoofCV is versatile, supporting various image types and offering extensive tools for tasks like geometric and photometric calibration, stereo vision, structure from motion, and image stabilization.

java for image processing

How to Set Up BoofCV

To set up BoofCV, you first need to ensure that you have the Java Development Kit (JDK) installed on your system. When adding BoofCV to your project, include BoofCV dependencies in your pom.xml file if you are using Maven. An example dependency in your pom.xml might look like this:

 <version>[Latest Version]</version>

For Gradle, add the dependency in your build.gradle file. Alternatively, you can manually download the JAR files directly from the BoofCV GitHub releases page and add them to your project’s classpath.

To verify the installation, create a simple Java class to import a BoofCV class (for example, boofcv.struct.image.GrayU8). If there are no import errors, the setup is successful.

How to Load an Image with BoofCV

To load an image using BoofCV, start by importing the necessary classes for file handling and image data structures, for example:

import boofcv.struct.image.GrayU8

You can use UtilImageIO to load an image from a file. For example, to load a grayscale image, use this code:

GrayU8 image = UtilImageIO.loadImage("path/to/image.jpg", GrayU8.class)

How to Edit an Image in BoofCV

Editing an image in BoofCV involves importing image processing classes relevant to the operations you need, such as filters or transformations.

For instance, use this code to apply a binary threshold to an image:

GrayU8 binary = new GrayU8(image.width,image.height);
GThresholdImageOps.threshold(image, binary, 100, true);

This code snippet converts a grayscale image into a binary image with a threshold value of 100.

After editing, save the modified image using this command:

UtilImageIO.saveImage(binary, "path/to/save/edited_image.jpg")

BoofCV offers a wide range of image processing operations, so you can experiment with different functions to achieve various effects, such as edge detection, smoothing, or geometric transformations.

Note: If you are using Maven, don’t forget to add JUnit as a dependency in your project.

2. JavaCV for Java Image Processing

JavaCV is a wrapper for commonly used libraries in computer vision, such as OpenCV, FFmpeg, and others. It offers a Java interface to these powerful native libraries, simplifying access to advanced capabilities in image processing and computer vision, like real-time filters, object detection, feature extraction, and video processing.

JavaCV is suitable for high-performance image processing applications and is widely used in academia and industry for research, prototyping, and production-grade projects.

How to Set Up JavaCV

To set up JavaCV, first make sure you have the JDK installed on your system. To add JavaCV to your project, if you’re using Maven, you need to include JavaCV’s dependencies in your pom.xml file. Here’s an example:

 <version>[Latest Version]</version>

For Gradle projects, add the dependency in your build.gradle file. You also have the option to download the JAR files directly from the JavaCV GitHub releases page and manually add them to your project’s classpath.

Once you have added the dependencies, create a simple Java class to import a JavaCV class, for example, org.bytedeco.opencv.opencv_core.Mat. If there are no import errors, installation is successful.

How to Load an Image with JavaCV

To load an image in JavaCV, begin by importing the necessary classes for image handling:

import org.bytedeco.opencv.opencv_core.Mat

You can load an image from a file using JavaCV’s opencv_imgcodecs.imread function. For example, to load an image into a Mat (matrix) object, use:

Mat image = opencv_imgcodecs.imread("path/to/image.jpg");

This function reads the specified file and loads the image into the Mat object.

How to Edit an Image in JavaCV

Editing an image with JavaCV involves using the library’s various image processing capabilities. First, import the necessary JavaCV classes for your intended operations. For example, if you want to convert an image to grayscale, you would import opencv_imgproc.

Here’s an example of how you might convert an RGB image to grayscale:

Mat grayImage = new Mat();
opencv_imgproc.cvtColor(image, grayImage, opencv_imgproc.COLOR_RGB2GRAY);

This code converts the image into a grayscale image stored in grayImage. After processing the image, you can save it as follows:

opencv_imgcodecs.imwrite("path/to/save/edited_image.jpg", grayImage);

JavaCV provides a broad spectrum of image processing functions, including filtering, transformations, and feature detection, allowing for extensive manipulation and analysis of images.

3. ImageJ for Java Image Processing

ImageJ is an open-source image processing program extensively used in the scientific community to analyze and process multidimensional images. It’s highly extensible, with thousands of plugins and scripts for performing a wide range of image processing tasks, data analysis, and visualization.

ImageJ supports a variety of image formats and offers functionalities such as image segmentation, geometric transformations, statistical analysis, and 3D visualizations.

How to Set Up ImageJ

To set up ImageJ, first, ensure you have a compatible version of Java installed on your system.

To install ImageJ, download the appropriate version for your operating system from the ImageJ website. The website offers versions for Windows, Mac OS, and Linux. After downloading, extract the files and run the ImageJ executable. No special installation process is required; ImageJ runs directly from the extracted folder.

For developers looking to integrate ImageJ into their Java projects, you can add ImageJ as a dependency. If you’re using Maven, include the dependency in your pom.xml file.

As an alternative, you can also download ImageJ packaged with Java here.

How to Load an Image with ImageJ

Loading an image in ImageJ is straightforward. After starting ImageJ, you can open an image file by clicking on File in the menu bar, then Open, and select the image file you want to load. ImageJ supports a wide range of image formats, including TIFF, JPEG, GIF, and PNG.

For programmatic access or if you’re writing a script or plugin, you can use ImageJ’s API to load images. For example, you can use the IJ.openImage(String path) method to load an image from a given file path. For example:

import ij.IJ;
import ij.ImagePlus;

ImagePlus image = IJ.openImage("path/to/image.jpg");

This method returns an ImagePlus object, which is a container for image data in ImageJ.

How to Edit an Image in ImageJ

Editing an image in ImageJ can be done both manually through the GUI and programmatically using ImageJ’s API. The GUI provides a wide range of tools and options for image processing, including filters, color adjustments, transformations, and analysis tools.

For scripting or plugin development, ImageJ’s API offers extensive capabilities for image manipulation. For example, to convert an image to grayscale programmatically, you would use the method as follows:

import ij.IJ;
import ij.ImagePlus;

ImagePlus image = IJ.openImage("path/to/image.jpg");, "8-bit", "");

This script loads an image and converts it to 8-bit grayscale. After processing the image, you can save it using the method:, "path/to/save/edited_image.jpg");

4. Image Processing in Java With Cloudinary

Cloudinary is a powerful Image and Video API platform that empowers developers to efficiently manage, optimize, transform, and deliver images and videos at scale. Its powerful features make it an ideal choice for developers seeking to streamline their media workflows and enhance the performance of their applications.

One of Cloudinary’s standout features is its ability to process images dynamically using URLs. You can apply a wide range of transformations by simply modifying the URL, such as resizing, cropping, and filtering. For example, to resize an image to 300×300 pixels, you can use the following URL structure:,h_300/sample.jpg

This approach allows for real-time image optimization without the need for pre-processing, making it perfect for applications requiring on-the-fly adjustments.

For more complex scenarios, Cloudinary also offers a robust API that can be integrated into your Java applications. Using the Cloudinary Java SDK, you can programmatically manage and transform images with ease. Here’s a quick example of how to upload and apply transformations to an image in Java:

import com.cloudinary.Cloudinary;
import com.cloudinary.utils.ObjectUtils;

Cloudinary cloudinary = new Cloudinary(ObjectUtils.asMap(
  "cloud_name", "your_cloud_name",
  "api_key", "your_api_key",
  "api_secret", "your_api_secret"));

Map uploadResult = cloudinary.uploader().upload("path/to/image.jpg", ObjectUtils.emptyMap());

Map transformation = ObjectUtils.asMap(
  "width", 300,
  "height", 300,
  "crop", "scale");

Map transformedImage = cloudinary.url().transformation(transformation).generate("path/to/image.jpg");

By leveraging Cloudinary’s dynamic URLs and Java SDK, developers can seamlessly integrate powerful image processing capabilities into their workflows, ensuring high-quality media delivery and optimized performance.

Unlock the full potential of your digital content with Cloudinary’s advanced editing and optimization tools. Sign up for free today!

Last updated: Jun 9, 2024