Idiosyncratic Imagery.

The traditional, Western way of approaching a painting is to treat it like a window. Linear perspective, developed during the Renaissance, even provided a scientific method for creating a sense of space opening up inside that picture window. But what if you scrapped the idea of the window, as modern painters did? And then decided to treat painting like a photograph or book? Perhaps you can see where we're headed, from the title of ''R. H. Quaytman: Spine, Chapter 20'' at the Neuberger Museum. Ms. Quaytman stands on the cutting edge of conceptual -- or, at this point, post-post-conceptual -- painting. ''Spine, Chapter 20'' serves as a sort of midcareer retrospective, although a highly idiosyncratic and self-reflexive one. It is both a chapter in, and a summary of, her career so far. [ABSTRACT FROM AUTHOR]