Tweaked backdrop image and animation

Tweaked the filters of the backdrop image; more contrast, less brightness and less saturation, this combined with a higher opacity at the end of the animation gives a cleaner brighter look than the previous blur version.

Animation has been tweaked in order to wait for the image to load while maintaining 0 opacity. This is due to a flickering issue when loading the backdrop image; The backdrop would momentarily flash and then disappear and then animate in. This seems to fix the issue.