How to Retrieve an InputStream from a BufferedImage in Java?

How can I retrieve an InputStream from a BufferedImage object in Java?

BufferedImage bigImage = GraphicsUtilities.createThumbnail(ImageIO.read(file), 300);
ImageInputStream bigInputStream = ImageIO.createImageInputStream(bigImage);

Retrieving an InputStream from a BufferedImage can be accomplished using ByteArrayOutputStream. Since BufferedImage does not directly support InputStream creation, we will convert it to a byte array and then to an InputStream.

import javax.imageio.ImageIO;
import javax.imageio.stream.ImageOutputStream;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

public class ImageStreamExample {
    public static ByteArrayInputStream getInputStreamFromBufferedImage(BufferedImage image) throws IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ImageOutputStream ios = ImageIO.createImageOutputStream(baos);
        ImageIO.write(image, "png", ios);
        ios.flush();
        return new ByteArrayInputStream(baos.toByteArray());
    }
}

Causes

• `ImageIO.createImageInputStream()` does not accept a `BufferedImage` as a parameter; it only works with `File`, `ImageReader`, or other image sources.
• BufferedImage needs to be written to an `OutputStream` before transforming it into an `InputStream`.

Solutions

• Use a `ByteArrayOutputStream` to write the `BufferedImage` to a byte array.
• Convert the byte array to a `ByteArrayInputStream` to obtain an InputStream.

Mistake: Using ImageIO.createImageInputStream() with BufferedImage

Solution: Use ByteArrayOutputStream to first write the BufferedImage and then convert it to InputStream.

Mistake: Not flushing the ImageOutputStream

Solution: Always flush the output stream after writing the image to ensure all data is flushed to the ByteArrayOutputStream.