灰度图画法

public 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; 
}