What's up guys...

Basically, I want to show a few characters in a photograph (which the main character is looking at) before I actually show them on screen.

The question is, do I introduce them as characters (as you normally would), or do you do it a different way?

The way I'd written was something like-

Theo looks at a photograph of him and an attractive women, EMMA (25), both posing intimately with each other for the camera.

Is the correct way to write it?

Toby.

That's how I did it with a script I entered at moviepoet. Nobody commented on it as being wrong, so I guess it's fine.

I guess the only thing that would change is if the picture was taken a long time ago, but if the character is pretty much the same age as in the photo, that should be fine mate.

The key here will be clarity and the way the audience perceives the picture. The way I wrote it once was that the picture contained the character looking at the picture as well as two men and two women, all about the some age, and then when those characters appeared, I noted that they were one of the people in the picture to make the relationship.

Just found it:
He [the character in the scene] picks up a photograph of himself with four other people: two men and two women, all about the same age. They are all posed for the picture in a park somewhere and are all smiles.

Later, as the characters appear, they go like this:
SUSAN TISDALE, one of the women from the picture, gets out of the car and stands in front of the house.

This way, you aren't telling about the picture, and you're drawing the relationship the audience is able to draw when you introduce the characters physically. The director/producer/whoever does the picture will figure out the photograph from the screenplay and construct it correctly. If layout is important, you may have to tell more than you show, though. With the pic you describe, you show go for the show and not give the character name just yet.