What does "vignette" mean?

Vignette: A decorative design, originally representing vine branches or tendrils, at the head of a chapter, of a manuscript or printed book, or in a similar position; hence, by extension, any small picture in a book; hence, also, as such pictures are often without a definite bounding line, any picture, as an engraving, a photograph, or the like, which vanishes gradually at the edge.