iPhoto: Tips for improving face recognition
The more images of a person you confirm, the better iPhoto becomes at finding the person in other photos.
Here are some guidelines.
Faces in profile: Name a face in profile to help iPhoto find and suggest more profile shots of that person. Make sure to identify full-face shots of that person as well, so that iPhoto can suggest both variations.
The same person at different ages: If you have photos of the same person spanning a significant period of time, such as from birth to grade-school age, you can help iPhoto suggest more matches by giving the same name to photos of that person at several different ages.
Blurry, badly lit, or really small faces: If iPhoto automatically detects a face even if it’s unclear, naming that face broadens the suggested photos for that particular person. However, in these types of photos, faces are harder to distinguish. Naming these faces may cause iPhoto to incorrectly suggest these faces for other people as well. If you want to stop iPhoto from unnecessarily broadening its search for matches, you can remove the name from that face. Select the photo and click the Info button in the toolbar to open the Information pane, and then see step 6 of the second task of this topic: Name the people in your photos.
Photos showing the backs of heads: It’s extremely unlikely that iPhoto would detect the back of a person’s head. If you want, you can manually identify a back-of-the-head shot as a “face.”