Vignette effect

We have decided that we need to emphasise the fact that the second half of our trailer is set in the past, as this will make the narrative even clearer. An example of a technique we could use is in The Wizard of Oz, in which the film goes from black and white to colour to demonstrate a change in location. However, we felt that a complete desaturation of colour in the second half of our trailer would be slightly too extreme; this was confirmed when we tried putting a black and white filter on the old part of the trailer, which just didn't look right. Fortunately, after trying out a few alternative video filters on the footage, we found one, the vignette effect, that was ideal; it gave a slightly blurred, green/brown hue to the edge of the footage, which really helped to create the sense that it was a  flashback into the past.