I do it a more ... difficult way, but then the pixel is just around the image and not on it like with stroke, just copy/copy merged, the image, then open a new image, and just make the height and length two/four/eight pixels longer (depends on the size u want to use, with two it's a 1 pixel border with four a 2 pixel etc. Then in the new image just paste your pic, and select the part that's blank, just fill that part and then u have a border around the image instead of on it.
grtz Naz