Hi guys

I'm looking for an app that will draw an outline (of my choice of color and thickness) around a picture. It would preferably need to support transparencies and .png files.

I am tired of exporting icons etc, drawing the outline, and then importing them again.

Thanks in advance.

edit: Sorry, I should have also specified that I would like to be able to auto-select an area (based on color for example) and then apply the outline or stroke. Something similar to 'stroke selection' in GIMP and Photoshop.