I have a vector image that I am trying to add a drop shadow to and export at 300dpi for print media. I create the elements and add Gaussian Blur Effect to them. I then export as a PNG image at 300dpi. When I view the PNG image all of the elements are sharp at 300dpi except the blured elements are pixelated. For some reason they're not getting rendered at 300dpi. It's like they're being rendered at 72dpi and scaled up. Is there a setting in Illustrator CS to change the base document dpi?