How do I resize my imageview within my scrollview as it is done in this image?

Question

There is simple example below that shows how to achieve parallax effect.

First, put your ImageView and other views into FrameLayout:

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/scrollView"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <FrameLayout
        android:id="@+id/flWrapper"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <ImageView
            android:id="@+id/contactPic"
            android:layout_width="match_parent"
            android:layout_height="@dimen/contact_photo_height"
            android:scaleType="centerCrop"
            android:src="@drawable/stock" />

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="@dimen/contact_photo_height">

            <!-- Other Views -->

        </LinearLayout>

    </FrameLayout>
</ScrollView>

LinearLayout's top margin is equal to the ImageViews's height (@dimen/contact_photo_height in our example).

Then we should listen scroll position of the ScrollView and change the position of ImageView:

@Override
protected void onCreate(Bundle savedInstanceState) {
    <...>

    mScrollView = (ScrollView) findViewById(R.id.scrollView);
    mPhotoIV = (ImageView) findViewById(R.id.contactPic);
    mWrapperFL = (FrameLayout) findViewById(R.id.flWrapper);

    mScrollView.getViewTreeObserver().addOnScrollChangedListener(new ScrollPositionObserver());

    <...>
}

private class ScrollPositionObserver implements ViewTreeObserver.OnScrollChangedListener {

    private int mImageViewHeight;

    public ScrollPositionObserver() {
        mImageViewHeight = getResources().getDimensionPixelSize(R.dimen.contact_photo_height);
    }

    @Override
    public void onScrollChanged() {
        int scrollY = Math.min(Math.max(mScrollView.getScrollY(), 0), mImageViewHeight);

        // changing position of ImageView
        mPhotoIV.setTranslationY(scrollY / 2);

        // alpha you could set to ActionBar background
        float alpha = scrollY / (float) mImageViewHeight;
    }
}