Hi I'm hoping someone can help me out here.

I've attached a bunch of .PNG images to my drawing, and they look fine in the layout and model views, but as soon as I plot to PDF they start doing all sorts of weird things, display incorrectly with some sort of shadow after-effect (see picture attached). I'm guessing it has something to do with the alpha values - I'm not sure.

On the left is the original PNG, and on the right is the jumbled mess it comes out as when plotting:

What on earth is going on here? Is there a known way to fix this? Any help would be much appreciated -  I'm fairly new to DraftSight and image formats in general. I'll try a few different formats or removing the alpha channels and see how I get on.