For some reasons not all of my photos from pictures is in iphoto. These are ones I imported from my pc about five years ago. they went to a place called pictures but did not end up in iphoto. It seems there are two places, yet I can access the ones that were from the PC
iPhoto doesn't display photos from the Pictures folder. Instead, you have to add them to iPhoto which houses pictures in the iPhoto Library (which is, perhaps confusingly so, located in the Pictures folder as a separate library). This would explain why they are in that folder and not in iPhoto.