Imaging God and getting one's due

In Genesis 9:6 God says:

Whoever sheds the blood of man, by man shall his blood be shed, for God made man in his own image.”

What does it mean to image God?  What happened to man’s likeness to God after the Fall?  How does the image of God inform the principle of proportionate justice set forth in God’s post-flood covenant with Noah?  And how does this square with the way of life in the kingdom of heaven set forth by Jesus in the Sermon on the Mount?  For answers, listen here.