Gordon Parks’s portrait of Mr. and Mrs. Albert Thornton Sr., an older black couple in their Mobile, Ala., home in 1956, appears to have little in common with the images we have come to associate with civil rights photography.

It is in color, unlike most photographs of the movement. Its subject matter was neither newsworthy nor historic, unlike more widely published journalistic images of the racial murders, police brutality, demonstrations and boycotts that characterized the epic battle for racial justice and equality.

Yet, as effectively as any civil rights photograph, the portrait was a forceful “weapon of choice,” as Mr. Parks would say, in the struggle against racism and segregation. He took the picture on assignment for a September 1956 Life magazine photo-essay, “The Restraints: Open and Hidden,” which documented the everyday activities and rituals of one extended black family living in the rural South under Jim Crow segregation.

While 20 photographs were eventually published in Life, the bulk of Mr. Parks’s work from that shoot was thought to have been lost. That is, until this spring, when the Gordon Parks Foundation discovered more than 70 color transparencies at the bottom of an old storage box, wrapped in paper and masking tape and marked, “Segregation Series.”

Not all of the “Segregation” photographs are as prosaic as the Thornton portrait. Some are ominous and intense, providing stark evidence of the unjustness of segregation and the ways it endangered democracy: the “colored only” signs that marginalized one community as assuredly as they enriched another; the backbreaking labor; the squalor and overcrowding; and the unequal, ramshackle accommodations.

But most of the images are optimistic and affirmative, like the portrait of Mr. and Mrs. Thornton. They focus on the family’s everyday activities, and their resolve to get on with their lives as normally as possible, in spite of an environment that restricts and intimidates: Mrs. Thornton cradling her newborn great-grandchild (below); her son, now a father himself, on a stroll with his children; a couple filling out tax returns; a Sunday church service (Slide 7); boys fishing in a creek; a woman and her granddaughter window shopping (Slide 2); teenagers hanging out in front of a country store; and mourners at a funeral ( Slide 12).

These quiet, compelling photographs elicit a reaction that Mr. Parks believed was critical to the undoing of racial prejudice: empathy. Throughout his career, he endeavored to help viewers, white and black, to understand and share the feelings of others. It was with this goal in mind that he set out to document the lives of the Thornton family, creating images meant to alter the way Americans viewed one another and, ultimately, themselves.

More than anything, the “Segregation Series” challenged the abiding myth of racism: that the races are innately unequal, a delusion that allows one group to declare its superiority over another by capriciously ascribing to it negative traits, abnormalities or pathologies. It is the very fullness, even ordinariness, of the lives of the Thornton family that most effectively contests these notions of difference, which had flourished in a popular culture that offered no more than an incomplete or distorted view of African-American life.

As the writer Thulani Davis observes, white Americans, in the civil rights era, had little awareness that black people “lived in a complete universe.” In our private lives “we were whole. We enjoyed a richness that the mainstream almost never showed, but that we took for granted just as white people did.”

As the holistic depiction of black life in the rural South in the “Segregation Series” demonstrates, the aspirations, responsibilities, vocations, and rituals of the Thornton family were no different from those of white Americans. Yet, these religious and law-abiding people, and others like them, were persecuted. It is this incongruity, made visible by Mr. Parks’s photographs, which may have appealed to the empathy and fairness of some of Life’s white readers. It challenged them to reconsider both their attitudes about segregation and the stereotypes they assigned to people who were little different from them.

The complete and positive images also helped to bolster the morale of blacks in the face of withering prejudice. This is one reason Mr. Parks’s quiet portrait of the Thorntons is an important civil rights image, demonstrating as it does the historic role of photography in black culture.

Throughout a century of oppression, photography served as a ray of light for black Americans, illuminating the humanity, beauty and achievements long hidden in the culture at large. By allowing a people to record and celebrate the affirmative aspects of their lives, the camera helped to countermand the toxic effects of stereotypes on their self-esteem.

One detail in Mr. Parks’s photograph of the Thorntons underscores the medium’s restorative power: the ornately framed picture of the couple that hangs on the wall above them. The image dates to the time of their marriage in 1903, when he was 29 and she was 17. A close examination reveals that it was spliced together from two separate images. And so, what first appears to be a wedding picture is, in fact, the restitution of a lost history. The image serves as both a commemoration of the couple’s union and a poignant metaphor of the resilience and urgency of their bond against a tide spanning decades of intolerance and adversity.

Another object, the coffee table in the foreground with family snapshots proudly displayed under its glass top, underscores photography’s esteemed place in black life. These details remind us of the extent to which blacks were able to represent themselves in a positive light, requiring neither the cooperation of the media nor the work of photographers like Mr. Parks, who died at age 93 in 2006.

As the popularity of inexpensive and easily accessible cameras swept across the nation in the 1900s, black Americans, like their white counterparts, relied on snapshots to document and memorialize their lives. Millions of blacks used their own cameras (and before that patronized a nationwide syndicate of black-owned photo studios) to accomplish for themselves what a century and a half of mainstream representation usually could not: the creation of positive, multifaceted images that could embolden a people against the forces of intolerance.

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Maurice Berger is research professor and chief curator at the Center for Art, Design and Visual Culture at the University of Maryland, Baltimore County, and consulting curator at the Jewish Museum in New York. He recently curated “For All the World to See: Visual Culture and the Struggle for Civil Rights” at the International Center of Photography. He is the author of 11 books, including a memoir, “White Lies: Race and the Myths of Whiteness.” He contributed text, along with Henry Louis Gates, Jr., Deborah Willis and others, to “Gordon Parks: Collected Works,” coming out in September from Steidl.

Follow him — @MauriceBerger — and @nytimesphoto on Twitter.