why me getDrawable is not working need help


package com.example.asfandnaveed.photofilter;

import android.content.Context;
import android.content.ContextWrapper;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.LayerDrawable;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.widget.ImageView;


public class MainActivity extends ActionBarActivity {

ImageView asfandImageView;
Drawable angryFace;
Bitmap bitmapImage;

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

asfandImageView =(ImageView) findViewById(R.id.asfandImageView);

angryFace = getResources().getDrawable(R.drawable.angrybird );
bitmapImage = ((BitmapDrawable) angryFace).getBitmap();
Bitmap newPhoto = invertImage(bitmapImage);
asfandImageView.setImageBitmap(newPhoto);

///saves image
MediaStore.Images.Media.insertImage(getContentResolver(), newPhoto, "title", "description");
}


public static Bitmap invertImage(Bitmap orignal){

Bitmap finalImage = Bitmap.createBitmap(orignal.getWidth() , orignal.getHeight() , orignal.getConfig());


int A , R , G , B ;
int pixelColor;
int height = orignal.getHeight();
int width = orignal.getWidth();

for (int y=0 ;y