I have a number of PNG files with transparency, but for technical reasons I need the expand the total canvas size of the image. I tried using XnConvert but I can not seem to work out how to do the canvas resize with out the new space being created being filed with a solid colour.
When making some screenshots to phrase my question properly I discovered the solution to this. Sorry to waste your time, but I thought I would still make the thread in case others come here who are equally as much a silly bunny.
This image shows a simple resize image and then resize canvas function... in the resize canvas function I have circled the value that controls transparency for the new space created when you increase the size of a canvas.