IN our age of digitally retouched selfies, Francis Bacon’s portraits come as a monumental shock. The faces in his paintings, which dissolve at every turn, are chilling, as a major show at the National Portrait Gallery demonstrates.

Visitors to Francis Bacon: Human Presence are greeted by his studies of papal figures and men in suits. In these works, Bacon encased his figures in the suggestions of boxes, which are known as “space-frames.” He also deployed a painting technique known as “shuttering” in which he added a series of vertical lines to the portrait.