When artists do self-portraits, they often portray themselves on a scale somewhere between anguish and mania — Van Gogh’s swirly, blue painting of himself with furrowed brows; Andy Warhol’s black-and-gold depiction of staring wild and ghoulish into nowhere — but Elizabeth Peyton presents a peaceful, if slightly somber, picture of herself, her dog, her book, her flip-flops, and her pool. A Peyton retrospective is on view at the New Museum through January 11.