Creating High Res Images from Renderings?

[visualizer]

Can anyone tell me how to create better quality high res images from my renderings. When I do a rendering I export the completed image from Chief Architect as a tiff image and it always has a resolution of 72dpi, regardless if I did the rendering in standard or high quality. Is there a way I can get that increased to say 300dpi so that I have a higher res image? I'm creating an advertisement for a newsletter so I want the quality to be top notch.

Thanks for any advice!

Wade
Chief Architect X3