Get Pixels from Image using Java

We will see how we can read an image using Java. We know there are several kinds of image formats such as JPEG, GIF, PNG, BMP, TIFF etc. Java has built-in Image I/O API in javax.imageio package and it can be used to load external image formats into its BufferedImage formats. By default, Image I/O supports image formats such as JPEG, PNG, GIF, BMP, WBMP. It can also be extensible to support additional image formats for TIFF and JPEG 2000.

Image I/O recognizes the contents of the file as a JPEG format image, and decodes it into a BufferedImage which can be directly used by Java 2D.

Image can be load or read using following code snippets, where imagePath is the full path with image name from where the image can be read.

try {
      BufferedImage bufferedImage = ImageIO.read(new File(imagePath));
    } catch (Exception e) {
      e.printStackTrace();
    }

 

You can save the below image for reading.
get pixels from image

Now I will put whole source code for reading pixels from an image file using Java. You can customize as per your requirements.

package in.webtuts.test;

import in.webtuts.image.utils.FileUtils;

import java.awt.image.BufferedImage;
import java.io.File;

import javax.imageio.ImageIO;

import com.sun.image.codec.jpeg.ImageFormatException;

public class ImageToPixels {

  /**
  *    Constants for image types or formats
  */
  private static final String IMAGE_EXT_JPG = "jpg";
  private static final String IMAGE_EXT_JPEG = "jpeg";
  private static final String IMAGE_EXT_PNG = "png";
  private static final String IMAGE_EXT_GIF = "gif";

  /**
  *    Exception message to be thrown when allowed image types are not read
  */
  public static final String IMAGE_ALLOW_TYPES = "Image types allowed - " + IMAGE_EXT_JPG + IMAGE_EXT_JPEG + IMAGE_EXT_PNG + IMAGE_EXT_GIF;

  /**
   * @param args
   */
  public static void main(String[] args) {
    /**
    *    Read the image, Desert.jpg, from Desktop/Pictures
    */
    BufferedImage bufferedImage = getImage("C:/Users/admin/Desktop/Chrysanthemum.jpg");
    /**
    * Get pixels from the above image and display in the console
    */
    int[][] pixels = getImageToPixels(bufferedImage);
    for (int i = 0; i < pixels.length; i++) {
      for (int j = 0; j < pixels[0].length; j++) {
        System.out.print(pixels[i][j] + " ");
      }
      System.out.println();
    }
  }

  /**
  *    Read image and return BufferedImage
  *    imageFullPath - full path of the image with image file name
  */
  public static BufferedImage getImage(String imageFullPath) {
    BufferedImage bufferedImage = null;
    try {
      if (imageFullPath == null) {
        throw new NullPointerException("Image full path cannot be null or empty");
      }
      /**
      *    Check if the selected file is an image
      */
      boolean isImage = isFileAnImage(imageFullPath);
      if (!isImage) {
        throw new ImageFormatException(IMAGE_ALLOW_TYPES);
      }
      String imagePath = imageFullPath;
      /**
      *    get BufferedImage and return it
      */
      bufferedImage = ImageIO.read(new File(imagePath));
    } catch (Exception e) {
      e.printStackTrace();
    }
    return bufferedImage;
  }

  /**
  * Get pixels in two dimensional array
  * bufferedImage - get the BufferedImage instance from the image
  */
  public static int[][] getImageToPixels(BufferedImage bufferedImage) {
    if (bufferedImage == null) {
      throw new IllegalArgumentException();
    }
    int h = bufferedImage.getHeight();
    int w = bufferedImage.getWidth();
    int[][] pixels = new int[h][w];
    for (int i = 0; i < h; i++) {
      /**
      * get pixels from image
      */
      bufferedImage.getRGB(0, i, w, 1, pixels[i], 0, w);
    }
    return pixels;
  }

  /**
  *    Check a file is an image
  * imageName - image file name with extension
  */
  private static boolean isFileAnImage(String imageName) {
    if (imageName == null) {
      throw new NullPointerException("Image full path cannot be null or empty");
    }
    File imageFile = new File(imageName);
    String ext = getFileExtension(imageFile);
    if (IMAGE_EXT_GIF.equalsIgnoreCase(ext) || IMAGE_EXT_JPEG.equalsIgnoreCase(ext) || IMAGE_EXT_JPG.equalsIgnoreCase(ext)
        || IMAGE_EXT_PNG.equalsIgnoreCase(ext)) {
      return true;
    }
    return false;
  }

/**
     * Get file extension from the file
     *
     * @param file
     *            - file
     */
    public static String getFileExtension(File file) {
        if (file == null) {
            throw new NullPointerException("Image file cannot be null");
        }
        String name = file.getName();
        int lastDotIndex = name.lastIndexOf(".");
        if (lastDotIndex > 0 && lastDotIndex < (name.length() - 1)) {
            return name.substring(lastDotIndex + 1).toLowerCase();
        }
        return "";
    }
}

 

Download below sample pixels from the above attached image file.

imagetopixels

That’s all. Thank you for reading this article.

Soumitra Roy Sarkar

I am a professional Web developer, Enterprise Application developer, Software Engineer and Blogger. Connect me on Roy Tutorials Twitter Facebook  Google Plus Linkedin Or Email Me

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