Image Enhancement of New Orleans Flood Areas

I took the before / after images of New Orleans and Lake Pontchartrain blanked the clouds, and enhanced the difference which gives a good estimate of the flooded land around the lake, including New Orleans.

The satellite images originated on;
http://earthobservatory.nasa.gov/ 

Difference Blue and Red are flooded areas, including New Orleans at the point of the arrow. 


Before ...
http://earthobservatory.nasa.gov/ 


After ...