Analysing Film Posters - Introduction

As part of my marketing campaign I will be creating a poster to help advertise my film. I have noticed that posters have similar conventions (conventions of the medium) regardless of the genre the film belongs to. 

I am going to have a look at posters for five films from different genres to test my initial observations and to see if there are indeed consistent conventions across posters. I have purposely chosen posters for films from different genres - which are:

'Submarine' - Coming-of-Age Drama

'The Exorcist' - Horror

'Spider-man 3' - Superhero

'Finding Nemo' - Animated Family Film

'The Hangover' - Comedy