# Resizing Raster Image

[TOC]

###### tags: `java` `imaging`

---

In terms of performance:

1. `java.awt.Graphics2D` – 34ms
2. Imgscalr – 143ms
3. `java.awt.Image.getScaledInstance()` – 235ms
4. Marvin – 361ms
5. Thumbnailator – 547ms

## `java.awt.Graphics2D`<SUP>[](https://docs.oracle.com/en/java/javase/11/docs/api/java.desktop/java/awt/Graphics2D.html)</SUP>

BufferedImage resizeImage(
	BufferedImage originalImage,
	int targetWidth,
	int targetHeight
) throws IOException {
	BufferedImage resizedImage = new BufferedImage(
		targetWidth,
		targetHeight,
		BufferedImage.TYPE_INT_RGB
	);

	Graphics2D graphics2D = resizedImage.createGraphics();

	// Optional: Influencing different image processing aspects and most importantly image quality and processing time
	graphics2D.setRenderingHint(
		RenderingHints.KEY_INTERPOLATION,
		RenderingHints.VALUE_INTERPOLATION_BILINEAR
	);

	graphics2D.drawImage(
		originalImage,
		0,
		0,
		targetWidth,
		targetHeight,
		null
	);

	graphics2D.dispose();
	return resizedImage;
}

## Imgscalr

<dependency>
	<groupId>org.imgscalr</groupId>
	<artifactId>imgscalr-lib</artifactId>
	<version>4.2</version>
</dependency>

### Simplest Way

BufferedImage simpleResizeImage(
	BufferedImage originalImage,
	int targetWidth
) throws Exception {
	return Scalr.resize(originalImage, targetWidth);
}

### Full `resize()` method

BufferedImage resizeImage(
	BufferedImage originalImage,
	int targetWidth,
	int targetHeight
) throws Exception {
	return Scalr.resize(
		originalImage,
		Scalr.Method.AUTOMATIC,
		Scalr.Mode.AUTOMATIC,
		targetWidth,
		targetHeight,
		Scalr.OP_ANTIALIAS
	);
}

## `java.awt.Image.getScaledInstance()`<SUP>[](https://docs.oracle.com/en/java/javase/11/docs/api/java.desktop/java/awt/Image.html#getScaledInstance(int,int,int))</SUP>

BufferedImage resizeImage(
	BufferedImage originalImage,
	int targetWidth,
	int targetHeight
) throws IOException {
	Image resultingImage = originalImage.getScaledInstance(
		targetWidth,
		targetHeight,
		Image.SCALE_DEFAULT // or Image.SCALE_SMOOTH
	);

	BufferedImage outputImage = new BufferedImage(
		targetWidth,
		targetHeight,
		BufferedImage.TYPE_INT_RGB
	);

	outputImage.getGraphics().drawImage(
		resultingImage,
		0,
		0,
		null
	);

	return outputImage;
}

## Marvin

<dependency>
	<groupId>com.github.downgoon</groupId>
	<artifactId>marvin</artifactId>
	<version>1.5.5</version>
	<type>pom</type>
</dependency>
<dependency>
	<groupId>com.github.downgoon</groupId>
	<artifactId>MarvinPlugins</artifactId>
	<version>1.5.5</version>
</dependency>

BufferedImage resizeImage(
	BufferedImage originalImage,
	int targetWidth,
	int targetHeight
) {
	MarvinImage image = new MarvinImage(originalImage);

	Scale scale = new Scale();
	scale.load();
	scale.setAttribute(
		"newWidth",
		targetWidth
	);
	scale.setAttribute(
		"newHeight",
		targetHeight
	);
	scale.process(
		image.clone(),
		image,
		null,
		null,
		false
	);

	return image.getBufferedImageNoAlpha();
}

## Thumbnailator

<dependency>
	<groupId>net.coobird</groupId>
	<artifactId>thumbnailator</artifactId>
	<version>0.4.17</version>
</dependency>

### Setting Output Quality in Percentage

BufferedImage resizeImage(
	BufferedImage originalImage,
	int targetWidth,
	int targetHeight
) throws Exception {
	ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

	Thumbnails.
		of(originalImage).
		size(
			targetWidth,
			targetHeight
		).
		outputFormat("JPEG").
		outputQuality(1).
		toOutputStream(outputStream);

	byte[] data = outputStream.toByteArray();

	ByteArrayInputStream inputStream = new ByteArrayInputStream(data);

	return ImageIO.read(inputStream);
}

### Batch Processing

Thumbnails.
	of(
		new File("path/to/directory").
			listFiles()
	).
	size(
		300,
		300
	).
	outputFormat("JPEG").
	outputQuality(0.80).
	toFiles(Rename.PREFIX_DOT_THUMBNAIL);

## 出處

- [How Can I Resize an Image Using Java?](https://www.baeldung.com/java-resize-image)