After many attempts I found what I was looking for in this layout. Even spaced LinearLayouts with automatically fitted ImageViews, with maintained aspect ratio. Works with landscape and portrait with any screen and image resolution.
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#ffcc5d00" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical">
<LinearLayout
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_weight="1"
android:layout_height="wrap_content">
<LinearLayout
android:orientation="vertical"
android:layout_width="0dp"
android:layout_weight="1"
android:padding="10dip"
android:layout_height="fill_parent">
<ImageView
android:id="@+id/image1"
android:layout_height="fill_parent"
android:adjustViewBounds="true"
android:scaleType="fitCenter"
android:src="@drawable/stackoverflow"
android:layout_width="fill_parent"
android:layout_gravity="center" />
</LinearLayout>
<LinearLayout
android:orientation="vertical"
android:layout_width="0dp"
android:layout_weight="1"
android:padding="10dip"
android:layout_height="fill_parent">
<ImageView
android:id="@+id/image2"
android:layout_height="fill_parent"
android:adjustViewBounds="true"
android:scaleType="fitCenter"
android:src="@drawable/stackoverflow"
android:layout_width="fill_parent"
android:layout_gravity="center" />
</LinearLayout>
</LinearLayout>
<LinearLayout
android:orientation="horizontal"
android:layout_weight="1"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<LinearLayout
android:orientation="vertical"
android:layout_width="0dp"
android:layout_weight="1"
android:padding="10dip"
android:layout_height="fill_parent">
<ImageView
android:id="@+id/image3"
android:layout_height="fill_parent"
android:adjustViewBounds="true"
android:scaleType="fitCenter"
android:src="@drawable/stackoverflow"
android:layout_width="fill_parent"
android:layout_gravity="center" />
</LinearLayout>
<LinearLayout
android:orientation="vertical"
android:layout_width="0dp"
android:layout_weight="1"
android:padding="10dip"
android:layout_height="fill_parent">
<ImageView
android:id="@+id/image4"
android:layout_height="fill_parent"
android:adjustViewBounds="true"
android:scaleType="fitCenter"
android:src="@drawable/stackoverflow"
android:layout_width="fill_parent"
android:layout_gravity="center" />
</LinearLayout>
</LinearLayout>
</LinearLayout>
</LinearLayout>
</FrameLayout>