After shooting at Sculpture By the Sea, I had three batches of photos: iPhone, card 1 and 2. I downloaded the first card into iPhoto, then synced my iPhone. My settings call for the last 5 iPhoto events to be synced to the iPhone. iTunes dutifully did so. These, however, were the raw files and not edited. Some hours later, after having downloaded the iPhone photos and the ones from the second card and fully editing all the photos, I synced the iPhone again to refresh it. iTunes did not re-optimise the photos, so I still had the old, unedited versions. No amount of deletion of photos and resyncing will change this.
You have to delete the optimised photos that iTunes created. iPhoto ’08 is my source of photos for the iPhone, so this procedure is specific to this application.
Make sure that iPhoto is closed. Navigate to your Pictures folder. Right-click the iPhoto Library icon and select Show Package Contents. Delete the contents of the iPod Photo Cache folder. Resync in iTunes and iTunes will optimise the photos again and you’ll have the latest versions. Note that if you’re using an earlier version of iPhoto, this folder may be in a folder called iPhoto Library or similar. Earlier versions didn’t package all the files and folders into one icon.
Moral of the story is to try to download and edit all your photos before you sync your iPod/iPhone, but this is a fix if you don’t.