a small illustrative sketch (as sometimes placed at the beginning of chapters in books)
<noun.artifact>
Vignette \Vi*gnette"\, v. t. To make, as an engraving or a photograph, with a border or edge insensibly fading away.
Vignette \Vi*gnette"\ (?; 277), n. [F. vignette, fr. vigne a vine. See {Vine}, and cf. {Vinette}.] 1. (Arch.) A running ornament consisting of leaves and tendrils, used in Gothic architecture.
2. 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.
3. A picture, illustration, or depiction in words, esp. one of a small or dainty kind. [Webster 1913 Suppl.]