User blog comment:Harbumz/Introducing Vignette, Wikia's New Thumbnailer/@comment-961279-20150212061327/@comment-24880673-20150212065927

Yes, vignette provides the ablitity to render images to a given dimension. You can learn more about the modes and parameters supported here. The quality depends on many factors-- the size of the original, the requested diminsions (is it bigger or smaller than the original), the type of image (JPEG, PNG, GIF), etc.

We are trying to do our best to balance the quality of the image rendered and the size of the image. If you find images that are suffering from quality issues in the thumbnailing, please let us know.