Peter Hujar (1934–1987) was a maker of compelling images. By “compelling,” I mean that they cannot be absorbed with a glance, and that once you engage with them, they require that you stay with them to work through the relationships of their various parts. This is the case even though the overall compositions of the 29 black-and-white pictures on display in “Peter Hujar: Second Avenue” at the Matthew Marks Gallery are extremely simple. It is the case, for example, of the two baby pictures included in the show.

Baby pictures are not what one ordinarily thinks of in connection with Hujar, but he used two archetypal baby picture poses and, by shooting them with his unique sensibility and identifiable style, made them distinctly Hujar images. The first one encountered at Matthew Marks is “Baby John McClellan” (1981), a picture of an infant lying on his stomach on a rumpled blanket. There are several formal characteristics that distinguish this photograph from innumerable snapshots in family albums, or on computer desktops, or on cell phone screens. It is black-and-white and, like almost all the other works in the exhibition, it is 14 3/4-by-14 7/8-inches; that, together with the somber tone and the careful quality of the printing, announce it as an art photograph.

What mostly sets it apart, though, is the expression on the infant’s face. The child seems to have bags under his eyes, as if from lack of sleep, and he looks at the camera with his eyebrows raised. He seems puzzled and a little troubled to have found himself in the world. He is not posing but engaged in some sort of dialogue with the photographer and, since he is too young to have language, he raises his eyebrows to query what is going on. He is cute, but not cute like the baby on jars of Gerber baby foods, who is well lit, wide-eyed, and generic. By establishing a relationship with him, Hujar has granted the child personhood, and so what we have is not a “baby picture” but a portrait of a very wee being.

In “Crying Boy” (1979), a naked toddler stands in a space bare of furniture or decoration and howls. As with the other pictures, there is a harsh quality to the lighting, the focus is sharp, and the printing allows for dark blacks, all of which work at cross-purposes with the figure of a vulnerable, handsome little boy. The child’s silent wail seems to be heard sub specie aeternitatis. Hujar had a special empathy for children because of his own troubled childhood: His father abandoned his mother before he was born, and he was raised for his first 10 years in rural New Jersey by his grandparents. They abused him while he was a child, and as an adult he felt a kinship with others who had endured similar experiences. His sympathy extended to the marginalized and distressed.

Many of the pictures at Matthew Marks make evident that Hujar was homosexual. A tightly cropped portrait of a young man experiencing some sort of pain is title “Orgasm” (1969). The man in “Seated Nude” (1978) has his arms draped over the back of his chair and his knees spread so that his erection is unavoidable. There are pictures of several of the personalities of the contemporaneous downtown art scene in drag: “Ethyl Eichelberger as Auntie Belle Emme” (1979), “Cindy Lubar as Queen Victoria” (1974), “Charles Ludlum as Camille” (1974), “Bearded Cockette” (1973). The apparently working-class quartet of “Felix, Clyde, Ronnie, Manny” (1975) stand bare-chested against the naked plaster wall, muscled objects of desire.

Hujar is often bracketed with Robert Mapplethorpe as a homosexual photographer, but despite their similar sexual orientations, they had quite different sensibilities. When Hujar moved in 1970 to his illegal loft on Second Avenue and 12th Street, he turned his back on the uptown world of commercial photography in which, at any rate, he was not succeeding, and developed a style of hard-edged, almost brutal, realism. His style is dark but lyrical, personal, and utterly without cant. Robert Mapplethorpe’s work smacks of glamour. Much of it depends on the shock value of its content that is taken in at a glance; once you get it, there is little else to see. There is a meretricious element of self-promotion that is completely alien to Hujar’s work. It was important to Peter Hujar that he be remembered not as a homosexual photographer, but as a photographer who was homosexual. His identity as an artist was primary.

The pictures of men in drag largely avoid the brittle gaiety of high camp that was endemic to the milieu in which they were taken; the reality of the cracked plaster wall and of the bare concrete floor that was the usual backdrop in the Second Avenue loft play against fantastical excess. And the faces are ridden with introspection, existential doubts, and unsayable thoughts that Hujar’s camera gives voice to. In “Self-Portrait, Seated” (1980), he is his own subject. A tall, handsome man, he sits in the loft’s simple chair, naked but with his hands in his lap so his sex is not exposed. His white flesh stands out against the dark, unlit wall behind him. His chest, arms, and legs are hairy, and his beard and hair somewhat unkempt. One eye is hidden in shadow, and the one visible eye is almost — but not quite — looking at the camera. He is thinking about the picture he is taking, but he is thinking about something else as well.

Until April 26 (523 W. 24th St., between Tenth and Eleventh avenues, 212-243-0200).