WALLS, by Deidi von Schaewen (Pantheon, $17.95). Deidi von Schaewen is fascinated by the aesthetic messages walls can deliver. She is a Berliner, though taken away as a baby early in World War II, and walls that divide have no messages she wishes to record. It is walls that still carry the imprint of life that she photographs - buildings on which the intimate marks of a missing neighbor are printed: stairs, fireplaces, brighter spots on the clinging wallpaper where pictures hung or wardrobes stood, the long black lines of chimney flues. The wall art revealed by demolition if fugitive, intense, abstract; disturbing in its suggestion of the violence that knocks down houses, the pathos of these two-dimensional diagrams of how people lived, the forced confrontation with violated provacy. There is another sort of wall she likes too, and these are an endangered species; wreckers' balls won't create more of them. They carry the large-scale advertisements that, from 1800 or earlier until a few decades ago, were painted on the sides of buildings to be read from far off, to remain for years, where now posters in multiples are slapped on a blank painted surface every few weeks. Any French village you enter still has its Byrrh or Dubonnet signs occupying the side of some farm shed or corner shop, but these thing are rarely refreshed today ("We want to be modern. We prefer that hose dirty old walls did not exist any longer," a company representative told her). She has found gigantic pinking shears in downtown New York; a haunting palimpsest of Swan Vesta match paintings on a London wall; a superb statement in red, yellow and black on the side of a French barn extolling a shoe of another era; the ghost of a 3-story baby whose Cheshire eat smile remains while the rest has faded - a French soap ad; an enormous hausfrau with a window recently punched in her jaw; messages painted one on another like bad reception on short wave; a superb series of ads for a dentifrice ("Dr. Pierre") no longer made, in which the inventor's head, shown as it looked around 1835, occupies the entire side of tall houses throughout France, his expression varying according to the painter. One of these she has photographed at various seasons when ivy half reveals, then completely obscures the doctor's face. This marvelous-book sends you into the street with opened eyes.