iPhone takes 7 MP photos instead of 12MP

I've been taking many photos with the rear camera, they've all been 12 MP, like they're supposed to be. Then I just took some photos yesterday with the front camera, and it said it was 7 MP instead of 12. Then I looked back in my library, and I saw that every time I took a photo with the front camera, it was 7 MP. And it's not a problem with the "info" showing incorrect information, it's a problem with the photo not being the correct resolution. I can tell that it's not a 12 MP photo. Does someone know what's going on here? Do I have a manufacturer defect in my iPhone?