Java如何实现图片的放大与缩小处理？

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Java处理图片：放大缩小、分层、灰度处理、变色调、红化、锐化图片。

java处理扩大与缩小图片

• ​​图片扩大与缩小​​
• ​​图片分层​​
• ​​图片灰度处理​​
• ​​图片变绿色负片​​
• ​​图片红化​​
• ​​图片锐化​​

java处理扩大与缩小图片

图片扩大与缩小

在​​java.desktop.javax.imageio​​包下有操作图片相关的类。

不过，这些ImageIO只支持一些常见的图片类型:​​jpg,png​​等。

​​Java SE ImageIO docs​​

使用起来也不难：

@Test
public void testUp1() throws IOException {
ClassPathResource classPathResource = new ClassPathResource("test.png");
BufferedImage bufferedImage = ImageIO.read(classPathResource.getInputStream());
BufferedImage image = new BufferedImage(2000,1100 , bufferedImage.getType());
Graphics2D graphics = image.createGraphics();
graphics.drawImage(bufferedImage, 0,0,2000,1100,null);
graphics.dispose();
OutputStream outputStream = new FileOutputStream("out.jpg");
ImageIO.write(image, "jpg", outputStream);
outputStream.flush();
outputStream.close();
}

我准备的图片是一张1200*800的图片，jpg格式。

接着，我们转为2000*1100的图片，格式不变。

这是放大。

如果是缩小，就修改目标长度和宽度。比如800*400

想想，还能做其他的操作吗？

图片分层

比如双层？

@Test
public void testUp1() throws IOException {
ClassPathResource classPathResource = new ClassPathResource("test.jpg");
BufferedImage bufferedImage = ImageIO.read(classPathResource.getInputStream());
BufferedImage image = new BufferedImage(800,800 , bufferedImage.getType());
Graphics2D graphics = image.createGraphics();
graphics.drawImage(bufferedImage, 0,0,800,400,null);
graphics.drawImage(bufferedImage, 0,400,800,400,null);
graphics.dispose();
OutputStream outputStream = new FileOutputStream("out.jpg");
ImageIO.write(image, "jpg", outputStream);
outputStream.flush();
outputStream.close();
}

图片灰度处理

在或者，图片变黑白？

依然是那张美女图。

@Test
public void testUp() throws IOException {
ClassPathResource classPathResource = new ClassPathResource("test.jpg");
BufferedImage bufferedImage = ImageIO.read(classPathResource.getInputStream());
ColorSpace space = ColorSpace.getInstance(ColorSpace.CS_GRAY);
ColorConvertOp op = new ColorConvertOp(space, null);
BufferedImage image = op.filter(bufferedImage, null);
OutputStream outputStream = new FileOutputStream("out.jpg");
ImageIO.write(image, "jpg", outputStream);
outputStream.flush();
outputStream.close();
}

图片变绿色负片

说实话，我不太了解图像相关的知识，所以，如果名字不对，请包涵。

@Test
public void testUp() throws IOException {
ClassPathResource classPathResource = new ClassPathResource("test.jpg");
BufferedImage bufferedImage = ImageIO.read(classPathResource.getInputStream());
ColorSpace space = ColorSpace.getInstance(ColorSpace.CS_CIEXYZ);
ColorConvertOp op = new ColorConvertOp(space, null);
BufferedImage image = op.filter(bufferedImage, null);
OutputStream outputStream = new FileOutputStream("out.jpg");
ImageIO.write(image, "jpg", outputStream);
outputStream.flush();
outputStream.close();
}

图片红化

@Test
public void testUp() throws IOException {
ClassPathResource classPathResource = new ClassPathResource("test.jpg");
BufferedImage bufferedImage = ImageIO.read(classPathResource.getInputStream());
ColorSpace space = ColorSpace.getInstance(ColorSpace.CS_PYCC);
ColorConvertOp op = new ColorConvertOp(space, null);
BufferedImage image = op.filter(bufferedImage, null);
OutputStream outputStream = new FileOutputStream("out.jpg");
ImageIO.write(image, "jpg", outputStream);
outputStream.flush();
outputStream.close();
}

图片锐化

@Test
public void testUp() throws IOException {
ClassPathResource classPathResource = new ClassPathResource("test.jpg");
BufferedImage bufferedImage = ImageIO.read(classPathResource.getInputStream());
ColorSpace space = ColorSpace.getInstance(ColorSpace.CS_LINEAR_RGB);
ColorConvertOp op = new ColorConvertOp(space, null);
BufferedImage image = op.filter(bufferedImage, null);
OutputStream outputStream = new FileOutputStream("out.jpg");
ImageIO.write(image, "jpg", outputStream);
outputStream.flush();
outputStream.close();
}