钢镚儿冲刺一周期第三天

一、说在前面

　　昨天完成并实现了对图片像素的褪色处理，但是效率不高，今天打算在网上通过学习来实现算法的优化。、

二、大体思路

　　由于自己的想法实现起来效率并不高，所以今天要通过在网上寻找相似的案例来尝试学习。

三、代码

　　

public class MainActivity extends Activity implements OnClickListener
{
    private Button but_old = null;
    private Button but_func = null;
    private ImageView iv_show = null;


    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.picture_tuise);

    @Override
    public void onClick(View v)
    {
        switch (v.getId())
        {
            case R.id.btn_one:
                func();
                break;
            case R.id.btn_two:
                iv_show.setImageResource(R.drawable.f);
                break;
        }

    }
    //褪色处理
    public void func()
    {
        Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.drawable.f);
        int width = bitmap.getWidth();
        int height = bitmap.getHeight();
        Bitmap base = Bitmap.createBitmap(width, height,bitmap.getConfig());
//        Bitmap B=toGrayscale(base);
        Canvas canvas = new Canvas(base);//以base为模板创建canvas对象
        canvas.drawBitmap(bitmap, new Matrix(),new Paint());

        for(int i = 0; i < width; i++)//遍历像素点
        {
            for(int j = 0; j < height*0.5; j++)
            {
                int color = bitmap.getPixel(i, j);

                int r = Color.red(color);
                int g = Color.green(color);
                int b = Color.blue(color);
                int a = Color.alpha(color);

                int avg = (r+g+b)/3;//RGB均值

                if(avg >= 150)//100可以理解为经验值
                {
                    base.setPixel(i, j,Color.argb(a, 255, 255, 255));//设为白色
                }
                else
                {
                    base.setPixel(i, j,Color.argb(a, 0, 0, 0));//设为黑色
                }
            }
        }
        bitmap.recycle();
        iv_show.setImageBitmap(base);
    }
   //理想优化（未完成）
    public static Bitmap toGrayscale (Bitmap bmpOriginal)
    {
        int width, height;
        height = bmpOriginal.getHeight();
        width = bmpOriginal.getWidth();

        Bitmap bmpGrayscale = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
        Canvas c = new Canvas(bmpGrayscale);
        Paint paint = new Paint();
        ColorMatrix cm = new ColorMatrix();
        cm.setSaturation(0);
        ColorMatrixColorFilter f = new ColorMatrixColorFilter(cm);
        paint.setColorFilter(f);
        c.drawBitmap(bmpOriginal, 0, 0, paint);
        return bmpGrayscale;
    }
}