Scanned color negative Image

You should invert it in your scanning software before importing it into Aperture.

Alternatively you can try here - they have some presets which should help get you started

http://theapertureblog.com/2012/01/02/a-preset-for-using-negatives-in-aperture/

An example how to create these presets using the "Curves" adjustment is here, see my recent post and the comments in this thread by Kibry Krieger and Frank Caggiano:

Re: How do you convert a negative digital image to a positive?

You get the basic negative-positive conversion by inverting the RGB curve, but it will need a lot of tweaking:

Regards

Léonie