The artist blew up the passages by a factor of at least twenty; the paintings' materiality comes into focus as the surface images lose resolution, further abstracting already cropped and isolated images. That is to say, we can hardly tell what these paintings are "of."Katy Siegel, Artforum, 2001, on Gursky's Untitled XI, 1999, a photo of a detail of a Van Gogh painting, printed at 2.7 x 2m.This diffusion into abstraction seems to operate as a metaphor for the materiality of the photograph, the way that photographic images reveal either grain, in straight photography, or pixels, in digital photography, when sufficiently enlarged.