I have no trouble empathizing.
I can tell (most of the time) when my family member, friend, pet, or whatever is happy, sad, or angry with me.
I can figure out, based on my own experiences, how someone is feeling if I know they just lost a loved one, won an award, had to skip a meal, or just got called a name.
My problem is when someone shows me a picture of someone and asks me how they're feeling. I'm not a telepath, so mind reading is out. I haven't talked to them, so asking them directly is out. I've never met the person, so I have no base line to go by. How should I know how they're feeling?
A NT can take a look at the same picture, and based on body language and facial expression and some sort of innate hocus pocus, tell you how that same person is feeling.