imageView= (ImageView) findViewById(R.id.iv);
try {
  inputStream= getAssets().open("fengjing.jpg");assets 資料夾 要建在 app目錄下。
} catch (IOException e) {
    e.printStackTrace();
}
BitmapFactory.Options options=new BitmapFactory.Options();
options.inJustDecodeBounds=true;//不載入進記憶體 只獲取圖片資訊。
BitmapFactory.decodeStream
 
(inputStream,null,options);
int w=options.outWidth;
int h=options.outHeight;
try {
    BitmapRegionDecoder bitmapRegionDecoder=BitmapRegionDecoder.newInstance(inputStream,true);
    BitmapFactory.Options op=new BitmapFactory.Options();
    op.inPreferredConfig= Bitmap.Config.RGB_565;
 Bitmap b=   bitmapRegionDecoder.decodeRegion(new 
 
Rect(w/2,h/2,w/2+300,h/2+200),options);
    imageView.setImageBitmap(b);
} catch (IOException e) {
    e.printStackTrace();
}