java png图片读取_png图片的读取

快来打我* 2022-11-03 11:23 413阅读 0赞

一、得到图片中的数据

1、现有一副png图片，提取其中某个区域的内容，保存成另外的图片。

![1350483525\_6610.jpg][1350483525_6610.jpg]

处理后云图如下，黑色的表示云。

![1350483609\_8680.png][1350483609_8680.png]

现在要得到河南省的的，比如区域的范围是(270,270)到(390,390)的区域。

import java.awt.BasicStroke;

import java.awt.Color;

import java.awt.Graphics;

import java.awt.Graphics2D;

import java.awt.GraphicsConfiguration;

import java.awt.GraphicsDevice;

import java.awt.GraphicsEnvironment;

import java.awt.HeadlessException;

import java.awt.Image;

import java.awt.Transparency;

import java.awt.image.BufferedImage;

import java.awt.image.ColorModel;

import java.awt.image.PixelGrabber;

import java.io.File;

import javax.imageio.ImageIO;

import javax.swing.ImageIcon;

public class LoadOneImage \{

public static void main(String\[\] args) \{

String myreadline = "";

// 定义一个String类型的变量,用来每次读取一行

try \{

myreadline = "mask\_cloud.png";// 读取一行

BufferedImage image = toBufferedImage(new ImageIcon("data/Image/"

\+ myreadline).getImage());

int height = image.getHeight();

int width = image.getWidth();

System.out.println("图片的高度为------>" + height);

System.out.println("图片的宽度为------>" + width);

// 创建BufferedImage对象

BufferedImage targetimage = new BufferedImage(1280, 1024,BufferedImage.TYPE\_INT\_RGB);

// 获取Graphics2D

Graphics2D g2d = targetimage.createGraphics();

// ---------- 增加下面的代码使得背景透明 -----------------

targetimage = g2d.getDeviceConfiguration().createCompatibleImage(

1280, 1024, Transparency.TRANSLUCENT);

// 释放对象

g2d.dispose();

g2d = targetimage.createGraphics();

// ---------- 背景透明代码结束 -----------------

for (int y = 270; y < 390; y++) \{

for (int x = 270; x < 390; x++) \{

Color color = new Color(image.getRGB(x, y));

if (color.equals(Color.BLACK))

g2d.setColor(Color.RED);

else

g2d.setColor(Color.BLUE);

g2d.setStroke(new BasicStroke(1));

g2d.drawLine(x, y, x, y);

// 释放对象

g2d.dispose();

ImageIO.write(targetimage, "png", new File("test.png"));

\} catch (Exception e) \{

e.printStackTrace();

System.out.println("结束");

// This method returns a buffered image with the contents of an image

public static BufferedImage toBufferedImage(Image image) \{

if (image instanceof BufferedImage) \{

return (BufferedImage) image;

// Determine if the image has transparent pixels; for this method's

// implementation, see e661 Determining If an Image Has Transparent

// Pixels

boolean hasAlpha = hasAlpha(image);

// Create a buffered image with a format that's compatible with the

// screen

BufferedImage bimage = null;

GraphicsEnvironment ge = GraphicsEnvironment

.getLocalGraphicsEnvironment();

try \{

// Determine the type of transparency of the new buffered image

int transparency = Transparency.OPAQUE;

if (hasAlpha) \{

transparency = Transparency.BITMASK;

// Create the buffered image

GraphicsDevice gs = ge.getDefaultScreenDevice();

GraphicsConfiguration gc = gs.getDefaultConfiguration();

bimage = gc.createCompatibleImage(image.getWidth(null), image

.getHeight(null), transparency);

\} catch (HeadlessException e) \{

// The system does not have a screen

if (bimage == null) \{

// Create a buffered image using the default color model

int type = BufferedImage.TYPE\_INT\_RGB;

if (hasAlpha) \{

type = BufferedImage.TYPE\_INT\_ARGB;

bimage = new BufferedImage(image.getWidth(null), image

.getHeight(null), type);

// Copy image to buffered image

Graphics g = bimage.createGraphics();

// Paint the image onto the buffered image

g.drawImage(image, 0, 0, null);

g.dispose();

return bimage;

// This method returns true if the specified image has transparent pixels

public static boolean hasAlpha(Image image) \{

// If buffered image, the color model is readily available

if (image instanceof BufferedImage) \{

BufferedImage bimage = (BufferedImage) image;

return bimage.getColorModel().hasAlpha();

// Use a pixel grabber to retrieve the image's color model;

// grabbing a single pixel is usually sufficient

PixelGrabber pg = new PixelGrabber(image, 0, 0, 1, 1, false);

try \{

pg.grabPixels();

\} catch (InterruptedException e) \{

// Get the image's color model

ColorModel cm = pg.getColorModel();

return cm.hasAlpha();

结果如下：

![1350484214\_8346.png][1350484214_8346.png]

其中黑色的用红色填充了，白色的用蓝色填充了。

[1350483525_6610.jpg]: https://img-my.csdn.net/uploads/201210/17/1350483525_6610.jpg
[1350483609_8680.png]: https://img-my.csdn.net/uploads/201210/17/1350483609_8680.png
[1350484214_8346.png]: https://img-my.csdn.net/uploads/201210/17/1350484214_8346.png