When I was working as a lecturer for the Institute for Industrial Design in Magdeburg, I organized a little cinema event called mitt|watch. Every week a movie would be selected by me, which had some connection to design. The title is a play on words between the English word watch and the German term Mittwoch (Wednesday), which was the day the event took place.
In order to announce the movie I wanted to have some kind of movie poster. As I did not like to simply show the cover of the DVD box, I developed a Processing program, which would extract the average color of every frame and write those as pixels in lines from top to bottom. This way I was able to “show” the whole movie on a sheet of paper. You could say, it is indeed a preview. After having exported a PDF out of Processing, I would then create the final poster in InDesign.
Thanks to amnon.owed on the Processing forums, who wrote the code for getting the average color of an image.