What hasn’t changed is that every photograph ever taken, digital as well as analog, is information. It doesn’t matter whether the subject of a given picture is momentous or trivial, whether it’s “real” or staged, whether the rendering is artful or pedestrian. Regardless of circumstance, what we see is a form of visual documentation: a particular person or set of persons, a particular object or set of objects, in a particular place at a particular time.

In our alpha-numeric culture, we most commonly associate information with words and numbers. But as a form of information, the visual qualifies just as much as those two do. Sometimes it does so even more: The phrase “worth a thousand words” might come to mind.

This information aspect of photography is so fundamental, even foundational, it gets taken for granted. It’s as basic, and intrinsic, as the need for a light source or the shape dictated by framing.

A new book and a celebrated photographer’s centenary are reminders of this photo-info nexus. Both take that connection even further. The book is “Sea of Files” (Steidl), by the Indian photographer Dayanita Singh. The birthday celebrant is Richard Avedon. Born on May 15, 1923, he died in 2004.

Singh’s title indicates the conceptual relevance information has to the work in question, the files being archival in nature. With Avedon, the relationship is nowhere near as straightforward. Photography as information defined his professional apprenticeship; and the ramifications of that defining remain visible — maybe “can be sensed” better states the case — throughout what would subsequently become the most glamorous of camera careers.

Singh, 62, won last year’s Hasselblad Award. A career honor, the Hasselblad is to photography as the Pritzker prize is to architecture. This year’s winner is Carrie Mae Weems. Other recipients have included Ansel Adams, Henri-Cartier Bresson, and, yes, Avedon. So Singh, a 2002 artist in residence at the Isabella Stewart Gardner Museum, is in excellent company.

Over four decades, she’s photographed musicians, family life, domestic interiors, city scenes, the Nehru family museum, economic privilege. What may be her most extraordinary subject is the heart of “Sea of Files”: several small, decrepit public archives.

“In India,” Singh explains, “there’s no one, single format for archives. Archivists design their own structures, whether it be metal or wood, and most of the time also design their own catalogue system. So there is great individuality there, and I love that.”

The images show that love, and you can understand why Singh would feel that way. The camera feasts on an endless tension between organization and disarray: the spilling out of folders, ledgers, registers, account books, stacks of documents tied together with string. They’re on shelves, in trunks, in sacks and bundles, on bare floors. Overhead are ceiling fans and fluorescent lights. Paint is peeling. Sometimes there’s a person present. Usually there isn’t, which adds to a general sense of abandonment.

This is where red tape goes to die — but not to be sold. That would be in Washington, D.C. The Washington Post reported in January that the National Archives gift shop — who knew that the National Archives had a gift shop — sells vintage red tape, the kind once used to bind government documents.

“Dickensian” is the word for these archival spaces, and the images feel as much literary as photographic: Melville’s “Bartleby, the Scrivener,” Kafka, Borges, Don DeLillo’s “Libra.” In that novel, a CIA archivist researches a secret history of the Kennedy assassination. His office could be a candidate for Singh’s camera: “There is nothing in the room he can discard as irrelevant or out-of-date. It all matters on one level or another. This is the room of lonely facts.” Lonely facts, like those found inside a photographic frame.

These photographs being in black-and-white underscores how alien the archives feel. In a Web-centric, info-saturated age, information is most commonly associated with pixels on a screen. Digital photographs are just one example of the seeming obsolescence of the physical tangibility of information storage. In this era of the prestidigitation that is digitation, the sheer, laundry-bag bulk of the contents of these archives is stunning. The archives don’t seem so much from an earlier time as from an alternate civilization, one with an altogether different understanding of how to store and retrieve information. Or maybe not-retrieving is the point: Just knowing that they exist is enough.

Repositories of information take many forms. Singh’s dusty archives are one kind. The spectacular library interiors that Candida Hofer photographs are another. Her sumptuous large-scale photographs are as much of a throwback to a pre-digital age as those in “Sea of Files” are. In an odd way, they’re as off-putting as Singh’s interiors. Those rooms at least feel lived in and are on a human, all-too-human scale. Hofer shows these magnificent libraries without users, emphasizing a sense of them as stage sets for information and culture.

Visually, Singh’s “Files” images have more in common with a photograph of a very different governmental archive. The filing cabinets that John Collier photographed in 1941 look utterly nondescript. Yet they contain treasures greater than those found in any of Hofer’s fabulous spaces. In those drawers are prints and negatives of the Farm Security Administration, a government agency tasked with documenting US society during the second half of the 1930s and early ‘40s. Its photographers included Walker Evans, Dorothea Lange, Arthur Rothstein, and Gordon Parks; and the photographs they took include some of the most famous of the last century. This is a photograph about photographic information, information of a very rare order.

Lange had strong views on the relationship between photography and information, specifically verbal. “All photographs — not only those that are so-called ‘documentary,’” she once said, “can be fortified by words.” She meant words as extension and elaboration. But fortifying can also apply to what’s seen within the frame.

A notably striking — and shaming — example is Lange’s photograph of an Oakland storefront. There’s a mailbox on the corner, a car parked in front. The words “Fruits and Vegetables” are above the door. An American flag is waving in the distance. Nothing out of the ordinary in any of that. Yet the date is March 1942, the owner of the store is Japanese American, and because of their heritage he and his family are about to be “relocated” to an internment camp. That explains the one unusual feature of the scene. “I AM AN AMERICAN” says the sign the owner has placed in the window. The information in Lange’s photograph was as disregarded then as anything in Singh’s archival rooms now. Except by the photographer.

Which brings us back to Richard Avedon. In his case, photography as information would have striking consequences. The same year Lange took that photograph Avedon enlisted in the Merchant Marine, serving as a photographer’s mate second class. Although he photographed the occasional training session and shipwreck, his duties mostly consisted of making ID photos. “I must have taken pictures of maybe 100,000 baffled faces,” he once said, “before it ever occurred to me that I was becoming a photographer.”

Over the decades, Avedon evolved a style of portraiture unmistakably his own, wherein a kind of null space — austere white background, black frame lines, no props — became a self-contained theater for his famous sitters: portraiture as the ultimate in ID photos. Next time you renew your license, keep Avedon’s professional beginnings in mind when you smile for the Registry camera.

“My photographs don’t go below the surface,” Avedon said. “They don’t go below anything. They’re readings of the surface. I have great faith in surfaces. A good one is full of clues.” A clue, of course, is a form of information waiting to be found out, photographically and otherwise.

Mark Feeney can be reached at mark.feeney@globe.com.