The reason that your chinese characters aren't being made into a stencil which surrounds them tightly is that the image you have loaded with the characters doesn't have a transparent background.
When you create a stencil from the contents of a layer, ArtRage puts a stencil around the area or colour on that layer. The chinese characters are a square block of colour so you get a square stencil. Your access granted image has a transparent background, so when you create a stencil you get only the letters.
You can also import images directly to your stencils ( via clicking 'import stencil' in the stencils panel and browsing to your image ). When you do this, black parts of images are used as the 'hole' in the stencil, and white parts are used as the 'plastic' of the stencil. Shades in between will let varying amounts of paint through. As your image background is not white, you will still get some paint bleeding through when you paint over a stencil added in this way however.
Resident Bug-Hunter and Support Guy