Java读取并修改图片的像素值

package work;

import java.awt.AWTException;
import java.awt.Dimension;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.image.BufferedImage;
import java.io.File;

import javax.imageio.ImageIO;

public class Image {
/**
* 读取一张图片的RGB值
*
* @throws Exception
*/
public void getImagePixel(String image) throws Exception {
int[] rgb = new int[3];
File file = new File(image);
BufferedImage bi = null;
try {
bi = ImageIO.read(file);
} catch (Exception e) {
e.printStackTrace();
}
int width = bi.getWidth();
int height = bi.getHeight();
int minx = bi.getMinX();
int miny = bi.getMinY();
System.out.println("width=" + width + ",height=" + height + ".");
System.out.println("minx=" + minx + ",miniy=" + miny + ".");
for (int i = minx; i < width; i++) {
for (int j = miny; j < height; j++) {
int pixel = bi.getRGB(i, j); // 下面三行代码将一个数字转换为RGB数字
rgb[0] = (pixel & 0xff0000) >> 16;
rgb[1] = (pixel & 0xff00) >> 8;
rgb[2] = (pixel & 0xff);
System.out.println("i=" + i + ",j=" + j + ":(" + rgb[0] + ","
+ rgb[1] + "," + rgb[2] + ")");
bi.setRGB(123, 123, 123);
}
}
}

/**
* 返回屏幕色彩值
*
* @param x
* @param y
* @return
* @throws AWTException
*/
public int getScreenPixel(int x, int y) throws AWTException { // 函数返回值为颜色的RGB值。
Robot rb = null; // java.awt.image包中的类，可以用来抓取屏幕，即截屏。
rb = new Robot();
Toolkit tk = Toolkit.getDefaultToolkit(); // 获取缺省工具包
Dimension di = tk.getScreenSize(); // 屏幕尺寸规格
System.out.println(di.width);
System.out.println(di.height);
Rectangle rec = new Rectangle(0, 0, di.width, di.height);
BufferedImage bi = rb.createScreenCapture(rec);
int pixelColor = bi.getRGB(x, y);

return 16777216 + pixelColor; // pixelColor的值为负，经过实践得出：加上颜色最大值就是实际颜色值。
}

/**
* @param args
*/
public static void main(String[] args) throws Exception {
int x = 0;
Image rc = new Image();
x = rc.getScreenPixel(100, 345);
System.out.println(x + " - ");
rc.getImagePixel("D:\\xiao.jpg");
}

}

package work;

import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;

public class Image1 {

private void setAlpha(String os) {
/**
* 增加测试项
* 读取图片，绘制成半透明,修改像素
*/
try {
ImageIcon imageIcon = new ImageIcon(os);
BufferedImage bufferedImage = new BufferedImage(imageIcon.getIconWidth(),imageIcon.getIconHeight()
, BufferedImage.TYPE_4BYTE_ABGR);
Graphics2D g2D = (Graphics2D) bufferedImage.getGraphics();
g2D.drawImage(imageIcon.getImage(), 0, 0,
imageIcon.getImageObserver());
//循环每一个像素点，改变像素点的Alpha值
int alpha = 100;
for (int j1 = bufferedImage.getMinY(); j1 < bufferedImage.getHeight(); j1++) {
for (int j2 = bufferedImage.getMinX(); j2 < bufferedImage.getWidth(); j2++) {
int pixel = bufferedImage.getRGB(j2, j1);
int[]   rgb = new int[3];
rgb[0] = (pixel & 0xff0000) >> 16;
rgb[1] = (pixel & 0xff00) >> 8;
rgb[2] = (pixel & 0xff);
System.out.println("i=" + j1 + ",j=" + j2 + ":(" + rgb[0] + ","
+ rgb[1] + "," + rgb[2] + ")");

pixel = ( (alpha + 1) << 24) | (pixel & 0x00ffffff);
bufferedImage.setRGB(j2, j1, pixel);
}
}
g2D.drawImage(bufferedImage, 0, 0, imageIcon.getImageObserver());

//生成图片为PNG
ImageIO.write(bufferedImage, "jpg",  new File("D:\\xiao.jpg"));
}
catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String[] args) throws Exception {
int x = 0;
Image1 rc = new Image1();
rc.setAlpha("D:\\xiao.jpg");
rc.setAlpha("D:\\xiao.jpg");
}

}