Blending with gradients?

Is this possible with the blender node comp system?

What i am want to do it blend to images together, but instead of an even blending im wanting it so that i can blend the middle of the image and not the out sides of each image, but have a smooth transition to each side.

Tell me if that doesnt make sense

Sorry, I don’t understand what you want. Try again?

http://mediawiki.blender.org/index.php/Manual/Map_To
Is this what you mean?

sure, use an AlphaOver node that has its Fac: fed by a horizontal gradient from black to white (not just a number, but an image); where it is black the image from the top input socket will be used; where white the bottom input image will be used. See the alphaover node toucan examples for the idea.