android从左到右平滑地改变图像的颜色

我想像光谱一样从左到右改变图像的颜色,并在颜色变化时看到颜色的变化,这是我的代码,问题是它在点击按钮后从原始图像变为最终图像,但我不知道如何改变它,这样我就可以看到变化。

final ImageView imgView = (ImageView) findViewById(R.id.imageView);
    Button btn = (Button) findViewById(R.id.button1);

    Bitmap bitmap = ((BitmapDrawable) imgView.getDrawable()).getBitmap();
    final Bitmap mutableBitmap = bitmap.copy(Bitmap.Config.ARGB_8888, true);

    btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View arg0) {


            for( x = 0; x < mutableBitmap.getWidth() ; x++){
                runOnUiThread (new Thread(new Runnable() { 
                     public void run() {
                         try {
                                        for(int y = 0; y < mutableBitmap.getHeight() ; y++){
                                            int c = mutableBitmap.getPixel(x, y);
                                            mutableBitmap.setPixel(x, y, Color.rgb(Color.red(c), (200 - Color.green(c)), Color.blue(c)));
                                            Log.d("IMAGE", ""+x);
                                        }   
                                        imgView.setImageBitmap(mutableBitmap);
                                            Thread.sleep(100);
                                        } catch (InterruptedException e) {
                                            // TODO Auto-generated catch block
                                            e.printStackTrace();
                                        }
                             }

                }));
            }
        }


    });