How do I soften the visible border of my projection?
Most digital projectors will create a visible edge to the projected image, even if the image is all all black. This border shows up because most projectors can’t actually project the color black as pure black.
The best way to soften the edges of your projection is to lower the contrast and brightness settings of your projector.
You may also want to consider making a "diffuser" for your projector using some cardboard and some wooden dowels. Here's a handy article about creating a "diffuser" effect for your decorations: