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。
处理后云图如下，黑色的表示云。
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：
其中黑色的用红色填充了，白色的用蓝色填充了。