There are many methods for adding a texture bleed, so I'll just briefly describe how I do it in Blender. Similar methods may work in other 2d graphics programs, or one might use built-in functionality in a texture painting software.

0) While still in Poser, make sure to render on a transparent background and save as PNG so that there's an alpha channel.

1) Load the image into Blender.

2) Duplicate the layer.

3) Select the bottom layer and remove the alpha channel. Now the bottom layer has a white background, while the top one still has transparency.

4) Still in the bottom layer, apply the "Erode" filter a few times. This will "bleed" the texture into the white background. It will also destroy the texture, but we still have the original in the top layer.

5) Make sure the layer mode for top layer is set to "Normal", flatten the image and save it.

-- I'm not mad at you, just Westphalian.