After 40 wonderful years, Mark Cohen has abruptly ended his relationship with his muse. It might seem like cold betrayal, but it’s really more complicated than that.

His muse isn’t a woman. It’s Wilkes-Barre, his Pennsylvania hometown, where he has been making stark street photographs since the 1970s. Last year Mr. Cohen, 71, moved to Philadelphia and into an apartment more manageable than the house where he raised his children and had his commercial studio.

His old romance was a black-and-white affair, literally, and he is showing some of those gritty images from the 1970s and 1980s at the Danziger Gallery in Manhattan. But this time he has included many lesser-known color photographs from the same era.

“I am mighty persistent in black-and-white, but I did experiment with color a number of times,” Mr. Cohen said. “I had a photography studio in Wilkes-Barre where I had to take color portraits of people, so I knew what color film was — but color photography in galleries didn’t happen until John Szarkowski made it happen.”

Actually, Mr. Cohen’s own artistic career happened thanks to Mr. Szarkowski, the fabled curator at the Museum of Modern Art, who gave him a solo exhibition of his black-and-white images in 1973. Soon, Mr. Cohen began using color negative film on the streets of Wilkes-Barre.

Color photography gained acceptance in the art world after Mr. Szarkowski staged a controversial show of William Eggleston’s work in 1976. Shortly afterward, William Jenkins, then curator of the George Eastman House in Rochester, arranged a supply of Kodak color negative film for Mr. Cohen and made 100 prints for the museum collection.

When a black-and-white volume aptly titled “Grim Street” was published in 2005, Mr. Cohen became a cult figure among younger street photographers. Though he subsequently published the book “True Color,” his reputation was solidly established as a black-and-white photographer.

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Beyond the palette, Mr. Cohen’s color photos look different from the earlier images showcased in the Danziger exhibit and also in the book “Dark Knees” that came out this year.

Around the time these color photos were taken, he switched from using a 28-millimeter to a 35-millimeter lens as his main tool for his aggressive street photography, and then to a 50-millimeter lens. Instead of shooting two to three feet from his subject, he would be four or five feet away, which is still very close for Wilkes-Barre, a down-on-its-luck small city in northeastern Pennsylvania without much street traffic.

“I started to move back because I was accosted by my subjects too frequently,” Mr. Cohen said. “After a while people started to push me around so I moved back a little bit. After all, there’s a limit to how many times you can tell people you’re an artist when they don’t get it.”

Although he has been taking pictures on the streets of Philadelphia, the relationship is still tentative. Philadelphians, it turns out, are not too accepting of his aggressive approach to street photography. When he walks up to strangers in the City of Brotherly Love, he often doesn’t get a fraternal embrace.

Even when the images are black-and-white, the relationship never is.

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“Mark Cohen” is on exhibition at Danziger Gallery in Manhattan until June 20.

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