After a bit of research, finding some good documentation and then testing these tools for myself, I can confirm that, yes, there are two secret editing tools in iPhoto.
So why are they a secret? The editing tools in iPhoto are for the most part single click effects and very simple to use. The secret editing tools really just add super powers to two of the tools that already exist: red eye fix and retouch. In exchange for these super powers, the tools become more complex to use. I have the feeling that Apple decided at the last minute to hide these super powers to keep the tools simple.
In a nutshell, here are the super powers gained by the secret tools:
- Retouch: You can change the size of the retouch brush from very small to very large and the amount of retouching from 0 to 100%. In addition, you can use the retouch tool to lighten areas of the image.
- Red eye fix: You can change the size of the area impacted by the red eye fix tool and also lighten the effect.
The article is somewhat long and involved, but if you want more detailed control when you edit your photos in iPhoto, it is good to know about these super secret super powers.