Currently Being ModeratedSep 21, 2012 11:09 PM (in response to Hoop88)
I found two ways to do this in Aperture, look at these links:
Use the Curves Controls in Aperture:
Create an Automator workflow:
Did you already scan the images? The scanner should do the inversion automatically.
Currently Being ModeratedSep 21, 2012 11:39 PM (in response to léonie)
I put a sample Aperture Library with the Curves Control saved as an Effect online. If you download this library (6 MB) and open it or import it into Aperture you should be able to use the "Negative" effect from the "Effects" drop down in the Adjustment Panel.
Download from here: http://dreschler-fischer.de/downloads/NegativeEffectTemplate.aplibrary.zip
To use the effect:
You may want to add a Color Monochrome adjustment, to remove all traces of color.