Increasingly, his paintings, drawings and prints emphasized the systems, processes and materials by which they were conceived and made. In the 1970s, he began to translate his photographic sources into pixelated images, filling in the individual cells of a grid with distinct marks, colors and tones that would cohere into photographic images when viewed from a distance. Using techniques and materials as various as watercolor, pastel, etching, handmade paper pulp and his own fingerprints, he continued to explore the dialogue between the physical facts and the photographic illusion.
His pragmatic, problem-solving approach would serve Mr. Close well in the second half of his career. In New York, on Dec. 7, 1988, he was felled by what turned out to be a collapsed spinal artery, which initially left him paralyzed from the neck down. In the ensuing months of rehabilitation, he began to regain movement in his arms, and he was able to sit up and paint using brushes strapped to his hand.
He not only returned to painting with unimpaired ambition but also began producing what many would view as the best work of his career. And he resumed his busy social life, attending gallery openings, giving talks around the country and attending exhibitions of his work in Europe and elsewhere.
In the years after his injury, Mr. Close painted in a looser way, partly because he had lost the fine motor coordination in his fingers. Even before the injury, however, he had been moving toward a brushier, more expressive and more colorful way of painting. Working on large gridded canvases prepared by assistants, he worked from left to right and top to bottom, filling each square of the grid with vibrant painted shapes resembling doughnuts, amoebas and hot dogs. Up close, the new paintings seemed to swarm with woozy, almost psychedelic energy, while from a distance the image would emerge in all its photographic exactness.
Mr. Close also expanded his list of subjects. He began to paint not only his closest friends and family members but also many other well-known artists, from veterans like Jasper Johns and John Chamberlain to younger comers like Cindy Sherman and Kara Walker. He became the New York art world’s court painter. Only once did he break his own rule of painting only other artists, immediate friends or family members: In 2006 he made a portrait of former President Bill Clinton, who had awarded him a National Medal of Arts in 2000.