I\'ve got a linear layout and an image...
Another method. (in Relative tested, but I think in Linear would be also works)
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:adjustViewBounds="true"
android:gravity="center"
If you use Eclipse you can choose graphical layout when *.xml file is active. On the top, you will find the Structure and option Adjust View Bounds. It will cut short all dimensions of pseudo-frame (blue rectangle) to size of your drawable file.
See also the scaleType option with make funny your image. Try it in Eclipse ;)