Been doing a bit of investigation of the ColorSync issues of iPhoto. I've found that if I apply a ColorSync profile (using Automator) such as "sRGB" and DO NOT check "Preserve original color space" that any edits in iPhoto will not remove this profile, i.e. it stays as sRGB. If the box is checked then on editing in iPhoto the profile will change to "Generic RGB Profile". This is the same as editing a photo without a profile in the first place.

However, it still doesn't change the problem of a slight colour[color] shift occuring when the sRGB profile is applied in the first place.

If you use ColorSync Utility you have three options (in the help):

  1. "Apply Profile" which doesn't actually change the ColorSync Profile, it just adjusts the image.
  2. Assign Profile. This is not meant to alter the image, only apply a profile
  3. Match Profile. Is meant to adjust the image to suit the new profile as well as applying it

I guess these correspond to the Automator Action and the check box. However, I wonder if there is a bug in the Automator action as the image looks the same whether or not "Preserve original color space" is selected? All Automator modified images look like the "Match Profile" option. So I guess for now, I'll go for that.