How change this target

Hello, I hope you can help me, I want to increase the image quality, could you guide me please.
Direct3D 9 render target is actually (-0.5,-0.5) to (639.5,359.5), increase the image quality, how could I?
Direct3D 9 render target is actually (-0.5,-0.5) to (639.5,359.5), increase the image quality, how could I?