Convert Image to Black and White using Java

This example demonstrates how to convert an image to Black and White using Java. A 1-bit image is created with an IndexColorModel with two colors in the default sRGB ColorSpace: {0,0,0} and {255,255,255}.

Convert Image to Black and White

We can obtain a BufferedImage by using the ImageIO.read() method. Next, we create a new BufferedImage with the same dimensions as the original and most impotently we pass in the BufferedImage.TYPE_BYTE_BINARY. This represents an image with 1-bit RGB colors: {0,0,0} and {255,255,255}. Finally, we draw the image using the Graphics2D.drawImage() method. The fourth argument Color.WHITE‘ll replace the transparent layer of a PNG into a default background.

package com.memorynotfound.image;

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

public class ConvertBlackWhite {

    public static void main(String... args) {

        try {

            File input = new File("/tmp/java-duke.png");
            BufferedImage image = ImageIO.read(input);

            BufferedImage result = new BufferedImage(
                    image.getWidth(),
                    image.getHeight(),
                    BufferedImage.TYPE_BYTE_BINARY);

            Graphics2D graphic = result.createGraphics();
            graphic.drawImage(image, 0, 0, Color.WHITE, null);
            graphic.dispose();

            File output = new File("/tmp/java-duke-black-white.png");
            ImageIO.write(result, "png", output);

        }  catch (IOException e) {
            e.printStackTrace();
        }

    }

}

Converted Images

To demonstrate the result, we added the following table. You can see that the result is rendered in only pure black and white 1-bit colors: {0,0,0} and {255,255,255}.

duke.png (original)	duke-black-white.jpg
Background: transparent	Background: white
Size: 9KB	Size: 1KB

References

• BufferedImage JavaDoc
• ImageIO JavaDoc
• BufferedImage.TYPE_BYTE_BINARY JavaDoc