The Sleeping Gypsy, Henri Rousseau
This was at one time (and probably still is) one of the most widely reproduced images in all of art. In most of those reproductions, however, you will find the colors “pushed”, so that the Gypsy’s multi-colored robe is a bright, eye-catching rainbow, belying the fact that this is intended to be a night scene. While Rousseau is considered a “naive” (untrained) artist, he was perfectly capable of distinguishing day from night.
But, hey — accuracy doesn’t sell posters.
I even have a bad (but at least dark) reproduction of it in my 2006 post on Henri Rousseau.
The MoMA website, on the other hand, has it too dark and desaturated, as are most of the website’s reproductions of work in their collections. (I haven’t yet figured out if this is the result of incompetence, lack of caring, or a deliberate attempt to discourage image use; but it’s a poor decision on their part, regardless, because it makes the images — and by extension the museum itself — look less appealing.)
I think the Google Art Project reproduction is as close as you will get to an accurate representation of this painting on the web.