Nearly everyone has heard the old saying that cameras—particularly TV cameras—"add ten pounds" to their subjects. Some people use it as a convenient excuse for those (real) ten extra pounds, but others believe that this claim has actual technical merit. There's a lot of confusion over how to explain this phenomenon, and whether it even exists in the first place, so I set out to investigate. Do modern cameras still make us look fatter?

Pixel myths

I went into this story based on something I was taught as an undergraduate—that video is what adds 10 pounds, not still photos, because of the type of pixels involved. Photographs are shot in square pixels and usually displayed on square pixel screens (your computer monitor, or occasionally printed out in square pixels), so they're not susceptible to this mysterious fattening phenomenon.

Video meant for the TV screen, however, isn't shot in the same way. Both NTSC and PAL pixels are rectangular (or non-square), and I was told that this is the reason why people look wider on TV. After all, if their images are being stretched horizontally, why wouldn't they? After digging around a bit, I learned that I wasn't the only one taught this at some point in my life.

It turns out that there are a number of reasons why this is wrong, at least on the NTSC side (NTSC is what we use here in the US). Yes, NTSC pixels are non-square, but they're not oriented horizontally—they're taller than they are wide. Additionally, the video is typically shot and displayed in NTSC, meaning that most of the time, there's opportunity to "stretch" the image in either direction—what you see is pretty much what you get.

PAL pixels, on the other hand, display at an aspect ratio of 1.066:1, meaning that they are wider than they are tall. Still though, if a video is shot in PAL and displayed in PAL, there should be no stretching. If it's shot in square pixels for whatever reason, though, and then converted into PAL, there could be some potential for those ten TV pounds to show up.

Optical illusions

More realistically, the explanation for the 10 extra pounds lies behind our eyes. For one, cameras have varying focal lengths, and most consumer cameras will slightly distort people in an image depending on where they are standing and how the photographer is holding the camera. As pointed out by Slate in 2007, wide-angle lenses have a short focal length that make the person in the center look both taller and wider, while those on the edges get the short end of the stick and just look wider. Cameras can also easily flatten a three-dimensional object into an unflattering two-dimensional space, tricking your eyes into thinking that a subject is spreading out by reducing depth while maintaining width.

When it comes to video, though, even professionally produced videos can play tricks on the eyes from time to time. Video professional and Ars reader Mike Watson entertained my barrage of questions on this topic, telling me that much of the video shot in a 4:3 aspect ratio doesn't show you the world the way you're used to seeing it. "Your eyes are placed on your face horizontally, so you get a 'widescreen' view of the world," he said. "TV—specifically, NTSC—is nearly square (4:3), so you are significantly modifying your view of the world, not just by 'zooming in' and isolating the TV in your view, but also by changing your entire perspective." Watson said that it's not hard to see how your brain might try to compensate for this by stretching things out a little, therefore making people look wider.

(Of course, this explanation doesn't really take into account the proliferation of widescreen TVs and, subsequently, widescreen-formatted HD video.)

In the end, though, most video pros ascribe the visual 10 pounds to bad lighting and bad angles. Light projected straight onto the subject (like, say, with a camera flash or some other amateurish lighting set up) will only help the camera flatten—and fatten—someone's image. Touching up photos to emphasize shadows can help, but better lighting from the get-go will do much more to flatter subjects.

Or, they could just lose 10 pounds and come out even.