java數(shù)字圖像處理基礎(chǔ)使用imageio寫圖像文件示例

2019-11-26 15:45:07

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一個(gè)BufferedImage的像素?cái)?shù)據(jù)儲(chǔ)存在Raster中，ColorModel里面儲(chǔ)存顏色空間，類型等信息，當(dāng)前Java只支持一下三種圖像格式- JPG,PNG,GIF,如何向讓Java支持其它格式，首先要完成Java中的圖像讀寫接口，然后打成jar，加上啟動(dòng)參數(shù)- Xbootclasspath/pnewimageformatIO.jar即可。

Java中如何讀寫一個(gè)圖像文件，使用ImageIO對(duì)象即可。讀圖像文件的代碼如下：

復(fù)制代碼代碼如下:

File file = new File("D://test//blue_flower.jpg");
BufferedImage image = ImageIO.read(file);

寫圖像文件的代碼如下：

復(fù)制代碼代碼如下:

File outputfile = new File("saved.png");
ImageIO.write(bufferedImage, "png",outputfile);

從BufferedImage對(duì)象中讀取像素?cái)?shù)據(jù)的代碼如下：

復(fù)制代碼代碼如下:

int type= image.getType();
if ( type ==BufferedImage.TYPE_INT_ARGB || type == BufferedImage.TYPE_INT_RGB )
return (int [])image.getRaster().getDataElements(x, y, width, height, pixels );
else
return image.getRGB( x, y, width, height, pixels, 0, width );

首先獲取圖像類型，如果不是32位的INT型數(shù)據(jù)，直接讀寫RGB值即可，否則需要從Raster
對(duì)象中讀取。

往BufferedImage對(duì)象中寫入像素?cái)?shù)據(jù)同樣遵守上面的規(guī)則。代碼如下：

復(fù)制代碼代碼如下:

int type= image.getType();
if ( type ==BufferedImage.TYPE_INT_ARGB || type == BufferedImage.TYPE_INT_RGB )
image.getRaster().setDataElements(x, y, width, height, pixels );
else
image.setRGB(x, y, width, height, pixels, 0, width );

讀取圖像可能因?yàn)閳D像文件比較大，需要一定時(shí)間的等待才可以，Java Advance Image
Processor API提供了MediaTracker對(duì)象來跟蹤圖像的加載，同步其它操作，使用方法如下：
MediaTracker tracker = new MediaTracker(this); //初始化對(duì)象
tracker.addImage(image_01, 1); // 加入要跟蹤的BufferedImage對(duì)象image_001
tracker.waitForID(1, 10000) // 等待10秒，讓iamge_01圖像加載
從一個(gè)32位int型數(shù)據(jù)cARGB中讀取圖像RGB顏色值的代碼如下：
1 int alpha = (cARGB >> 24)& 0xff; //透明度通道
2 int red = (cARGB >> 16) &0xff;
3 int green = (cARGB >> 8) &0xff;
4 int blue = cARGB & 0xff;
將RGB顏色值寫入成一個(gè)INT型數(shù)據(jù)cRGB的代碼如下：
cRGB = (alpha << 24) | (red<< 16) | (green << 8) | blue;
創(chuàng)建一個(gè)BufferedImage對(duì)象的代碼如下：
BufferedImage image = newBufferedImage(256, 256, BufferedImage.TYPE_INT_ARGB);
一個(gè)完整的源代碼Demo如下：

復(fù)制代碼代碼如下:

package com.gloomyfish.swing;

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.JComponent;
import javax.swing.JFrame;

public class PlasmaDemo extends JComponent {

    /**
     *
     */
    private static final long serialVersionUID = -2236160343614397287L;
    private BufferedImage image = null;
    private int size = 256;

    public PlasmaDemo() {
        super();
        this.setOpaque(false);
    }

    protected void paintComponent(Graphics g) {
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2.drawImage(getImage(), 5, 5, image.getWidth(), image.getHeight(), null);
    }

    private BufferedImage getImage() {
        if(image == null) {
            image = new BufferedImage(size, size, BufferedImage.TYPE_INT_ARGB);
            int[] rgbData = new int[size*size];
            generateNoiseImage(rgbData);
            setRGB(image, 0, 0, size, size, rgbData);
            File outFile = new File("plasma.jpg");
            try {
                ImageIO.write(image, "jpg", outFile);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return image;
    }

    public void generateNoiseImage(int[] rgbData) {
        int index = 0;
        int a = 255;
        int r = 0;
        int g = 0;
        int b = 0;

        for(int row=0; row<size; row++) {
            for(int col=0; col<size; col++) {
                // set random color value for each pixel
                r = (int)(128.0 + (128.0 * Math.sin((row + col) / 8.0)));
                g = (int)(128.0 + (128.0 * Math.sin((row + col) / 8.0)));
                b = (int)(128.0 + (128.0 * Math.sin((row + col) / 8.0)));

                rgbData[index] = ((clamp(a) & 0xff) << 24) |
                                ((clamp(r) & 0xff) << 16) |
                                ((clamp(g) & 0xff) << 8)   |
                                ((clamp(b) & 0xff));
                index++;
            }
        }

    }

    private int clamp(int rgb) {
        if(rgb > 255)
            return 255;
        if(rgb < 0)
            return 0;
        return rgb;
    }

    public void setRGB( BufferedImage image, int x, int y, int width, int height, int[] pixels ) {
        int type = image.getType();
        if ( type == BufferedImage.TYPE_INT_ARGB || type == BufferedImage.TYPE_INT_RGB )
            image.getRaster().setDataElements( x, y, width, height, pixels );
        else
            image.setRGB( x, y, width, height, pixels, 0, width );
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Noise Art Panel");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().setLayout(new BorderLayout());

        frame.getContentPane().add(new PlasmaDemo(), BorderLayout.CENTER);
        frame.setPreferredSize(new Dimension(400 + 25,450));
       frame.pack();
       frame.setVisible(true);
   }
}