Most curators hope to get glowing reviews and popular acclaim when they mount an exhibit. Michael Kamber, on the other hand, is expecting some blowback for his latest show, “Altered Images: 150 Years of Posed and Manipulated Documentary Photography,” which opens this weekend at the Bronx Documentary Center.

And he’s perfectly O.K. with that.

“I think there will be some unhappy people,” said Mr. Kamber, a photojournalist and founder of the center. “That’s good. If people would stop faking photos, then they wouldn’t have to be worried about being called out.”

The exhibit, a selection of well-known images that have been altered, staged or faked, is an indictment of some modern practices, and practitioners, of photojournalism. At a time when veteran photographers are being replaced by newcomers or untrained “citizen journalists,” it also raises important questions about the profession’s future amid increasing doubts about the veracity of images.

Mr. Kamber, who covered the Iraq and Afghanistan wars and conflicts in Africa for The New York Times, would be infuriated whenever he saw photographers pose images in the field or alter them in postprocessing.

“I’ve lost friends who put their lives on the line to get it right, and then you have people faking it,” said Mr. Kamber, who was close to both Tim Hetherington and Chris Hondros, who were killed in Libya. “It’s a betrayal. Just get it right. Don’t change things, don’t direct your subjects, don’t lie in your captions, don’t move pixels. Get it right. That’s what we’re here to do.”

The exhibit, which consists of more than 40 images, catalogs some of the darker moments in the history of photojournalism. And there is enough material to leave many news organizations red-faced: National Geographic for digitally moving Egyptian pyramids; Time magazine for darkening O. J. Simpson’s skin color; Magnum and Pictures of the Year International for a dramatic award-winning image by Paolo Pellegrin with a misleading caption (below); Associated Press and Reuters for moving digitally altered scenes from the Middle East; and The New York Times for publishing a posed photograph in 2002 of a boy holding a toy gun outside an Arabian-foods grocery.

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More recently, during the rioting in Baltimore after the death of Freddie Gray, who was injured while in police custody, an image circulated widely on social media that purported to show the city burning. It had actually been taken in Venezuela.

During this year’s World Press photo contest, about 20 percent of the entrants that reached the second-to-last round of judging were disqualified for significantly altering images in post processing and Giovanni Troilo was stripped of a first prize in the face of charges of misrepresentation and posing images (the photographer said he had “made a mistake,” but had not intended to deceive). In the vigorous debate that followed, some ridiculed the concept of “objective photojournalism” as philosophically tenuous in a postmodern world.

Mr. Kamber said he was inspired to do the show when Phil Leonian, a longtime New York studio photographer, called him in the aftermath of the debate over manipulated images in the World Press contest. Mr. Leonian encouraged him to mount an exhibit and financed it.

The exhibit shows that there have been ethical issues from the very beginning of photojournalism. Roger Fenton’s “Valley of the Shadow of Death,” made in 1855 during the Crimean War, was the first well-known conflict photograph and a forerunner of modern photojournalism. But there are two negatives taken by Mr. Fenton at the same location — one showing the road littered with cannonballs and the other with the cannonballs at the side of the road, which means that someone moved them.

The show also refers to Robert Capa’s classic “Falling Soldier” photo from the Spanish Civil War, an image that has been widely challenged as staged.

Posing was common in 19th-century conflict photos by Mr. Fenton and the Civil War photographers Mathew Brady and Alexander Gardner. Smaller cameras and faster film in the 1930s allowed photographers to stop motion and capture candid moments, which, in turn, spurred a set of ethical standards that demanded accuracy in journalistic photographs.

But as 20th-century technology allowed for more “truthful” images, the advent of digital photography has made it easier to produce misleading images. There are more cases of posed and manipulated images today than ever before, Mr. Kamber said.

“I think the main reason is that photography is a lot more democratic today and I think that’s great,” Mr. Kamber, 51, said. “But 20 years ago there were more staff photographers, and they knew very clearly that altering a photo was a fireable offense. Newspapers are laying off photographers by the hundreds, and there are all these young freelancers who have not been properly trained in what is or is not allowable or ethical.”

When Mr. Kamber was a young freelancer, his editors looked at his contact sheets and could more easily tell if a photograph had been posed by studying the frames before and after. Today photojournalists send in single images from the field and can easily alter them on their laptop or smartphone.

Mr. Kamber proudly admits that he is from “the old school” and sees good journalism as the front line of democracy. The public must have faith in the veracity of photojournalists, he said.

“People say that using a different lens or moving two feet to the left will change the perspective,” Mr. Kamber said. “Sure, but there has to be some integrity. I have to know that what I’m seeing on the page was exactly what was in front of you when you snapped the shutter and that you did not set the photo up or manipulate it.”

The exhibit, of which Bianca Farrow was a co-curator, is not intended to impose a viewpoint, but to prompt discussion about what is and is not allowable in photojournalism and documentary photography.

“Different news organizations have different standards and different contests have different standards,” Mr. Kamber said. “This is a discussion that we must have before we’ve destroyed all credibility in photojournalism.”

“Altered Images: 150 Years of Posed and Manipulated Documentary Photography,” will be open from this weekend at the Bronx Documentary Center until Aug. 2.

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