system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: I feel like I'm decent looking but why do I look uglier in pictures?

Not an insecure post. Just a general question. I think I'm decent looking when I look at myself in the mirror, but when I see pictures of myself I don't like them. Most of the time I find myself looking uglier than what I think I look like. Also some of my features in the mirror look good but when I see pictures they stick out. Like my hairline. I feel like I'm going bald when I see my pictures, but it seems fine when I look at myself in the mirror. 

I have to "pose" and stand on an angle and stuff to get a picture. But when I'm standing in front of the mirror, I have no issues about how I look. 

It's like your voice. When you listen to a recording it doesn't sound anything like you think it sounds.
gpt
Your image in the mirror is what you're used to seeing.  It's what your mental image of yourself looks like.  In your mind, your image in the mirror **is** you.

However, almost no one has a completely symmetrical face, and when you look at a picture, you're seeing a non-mirrored image of yourself that doesn't quite match your mental image of what you look like. So since it doesn't look like "you", you view it as being less attractive.

Although it might surprise you to know that your friends and family have the opposite opinion.  They're used to seeing your non-mirrored face, so to them, your image in the mirror is the less-attractive one.