Android-如何將RGB彩色圖轉換為灰度圖方法介紹

2020-04-11 12:41:46

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來源：轉載

供稿：網友

實例：RGB2Grey

項目運行效果圖：

源代碼：

[java]
public class MainActivity extends Activity {

    /* (non-Javadoc)
     * @see android.app.Activity#onCreate(android.os.Bundle)
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //通過Id來獲取界面中組件的引用
        Button rgb2greyBtn = (Button) findViewById(R.id.rgb2greybtn);
        ImageView imageView1 = (ImageView) findViewById(R.id.imageView1);
        final ImageView imageView2 = (ImageView) findViewById(R.id.imageView2);
        //通過位圖工廠，創建一個位圖
        final Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_android);
        imageView1.setImageBitmap(bitmap);
        //為“轉換為灰度圖”按鈕添加監聽事件
        rgb2greyBtn.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                //將轉換過后的灰度圖顯示出來
                imageView2.setImageBitmap(convertGreyImg(bitmap));
            }
        });

    }

    /**
     * 將彩色圖轉換為灰度圖
     * @param img 位圖
     * @return 返回轉換好的位圖
     */
    public Bitmap convertGreyImg(Bitmap img) {
        int width = img.getWidth();         //獲取位圖的寬
        int height = img.getHeight();       //獲取位圖的高

        int []pixels = new int[width * height]; //通過位圖的大小創建像素點數組

        img.getPixels(pixels, 0, width, 0, 0, width, height);
        int alpha = 0xFF << 24;
        for(int i = 0; i < height; i++) {
            for(int j = 0; j < width; j++) {
                int grey = pixels[width * i + j];

                int red = ((grey & 0x00FF0000 ) >> 16);
                int green = ((grey & 0x0000FF00) >> 8);
                int blue = (grey & 0x000000FF);

                grey = (int)((float) red * 0.3 + (float)green * 0.59 + (float)blue * 0.11);
                grey = alpha | (grey << 16) | (grey << 8) | grey;
                pixels[width * i + j] = grey;
            }
        }
        Bitmap result = Bitmap.createBitmap(width, height, Config.RGB_565);
        result.setPixels(pixels, 0, width, 0, 0, width, height);
        return result;
    }
}

public class MainActivity extends Activity {

    /* (non-Javadoc)
     * @see android.app.Activity#onCreate(android.os.Bundle)
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //通過Id來獲取界面中組件的引用
        Button rgb2greyBtn = (Button) findViewById(R.id.rgb2greybtn);
        ImageView imageView1 = (ImageView) findViewById(R.id.imageView1);
        final ImageView imageView2 = (ImageView) findViewById(R.id.imageView2);
        //通過位圖工廠，創建一個位圖
        final Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_android);
        imageView1.setImageBitmap(bitmap);
        //為“轉換為灰度圖”按鈕添加監聽事件
        rgb2greyBtn.setOnClickListener(new OnClickListener() {

   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    //將轉換過后的灰度圖顯示出來
    imageView2.setImageBitmap(convertGreyImg(bitmap));
   }
  });

    }

    /**
     * 將彩色圖轉換為灰度圖
     * @param img 位圖
     * @return 返回轉換好的位圖
     */
    public Bitmap convertGreyImg(Bitmap img) {
    int width = img.getWidth();   //獲取位圖的寬
    int height = img.getHeight();  //獲取位圖的高

    int []pixels = new int[width * height]; //通過位圖的大小創建像素點數組

    img.getPixels(pixels, 0, width, 0, 0, width, height);
    int alpha = 0xFF << 24;
    for(int i = 0; i < height; i++) {
      for(int j = 0; j < width; j++) {
       int grey = pixels[width * i + j];

       int red = ((grey & 0x00FF0000 ) >> 16);
       int green = ((grey & 0x0000FF00) >> 8);
       int blue = (grey & 0x000000FF);

       grey = (int)((float) red * 0.3 + (float)green * 0.59 + (float)blue * 0.11);
       grey = alpha | (grey << 16) | (grey << 8) | grey;
       pixels[width * i + j] = grey;
      }
    }
    Bitmap result = Bitmap.createBitmap(width, height, Config.RGB_565);
    result.setPixels(pixels, 0, width, 0, 0, width, height);
    return result;
    }
}

布局文件：

[html]
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/LinearLayout1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        />
    <Button
        android:id="@+id/rgb2greybtn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/rgb2greybtn"
        android:layout_gravity="center_horizontal"/>
    <ImageView
        android:id="@+id/imageView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        />"
</LinearLayout>