Freshly done up with robin’s egg blue walls and comfortable seating, the photography galleries at the Minneapolis Institute of Arts are atwitter with possibility as the museum celebrates its 100th anniversary and looks to the century ahead.

One possibility is signaled by a gap in the current show, “100+: A Photograph for Every Year of the MIA.” Marked by a mural-sized swirl of gray paint, it is a placeholder for a new commission by a “Surprise Artist.” Stay tuned.

Spring promises aside, however, “100+” is a curiously unsatisfying show, especially for a centennial exhibit that reasonably would be expected to tout the photography department’s current strengths and future vision. The show, organized by MIA photo curator David Little, runs through Oct. 18.

Picked from the department’s 12,000 images, the display features one picture taken each year since the museum opened in 1915. It includes an impressive roster of famous names, among them Ansel Adams, Brassaï, Robert Doisneau, Robert Frank, Thomas Struth, Eliot Porter and Sebastião Salgado.

Minnesotans get good play, too, with pictures by Tom Arndt, Jerome Liebling, Cory Prahl, Chris Faust, Alec Soth, Ray Muxter, Jim Henkel, Stuart Klipper, Xavier Tavera and JoAnn Verburg.

Nevertheless, the show is a confusing mess. The arrangement of photos is capricious and jokey. Color photos mix with black-and-white, big with little; frames are jammed together or oddly spread apart or stacked high on the wall. Weird ovals of gray paint float across some walls like gigantic cartoon speech bubbles dotted with pictures rather than words.

The jumble of sizes, subjects and styles could be expected in a chronological hanging of images by various artists acquired by different curators from many sources over a long period. But, inexplicably, the show is not arranged chronologically, as the show’s premise might lead visitors to expect. Dates are jumbled throughout and photos arranged arbitrarily or in vague, sometimes amusing, thematic clumps — hands (across face, tangled in string, holding food); landscape bits (blossoms, leaves, woods); animals (pig, penguins, dogs).

Formalist pairings materialize occasionally. Edward Steichen’s famous 1927 image of undulating dark-and-light sculpture in Brancusi’s Paris studio hangs above Ruth Bernhard’s 1963 “Two Forms,” an eloquent study of a black-and-white couple whose bodies echo the lines of Brancusi’s sculpture. But another design-duo very awkwardly ties Ralph Steiner’s 1922 close-up of typewriter keys to a pile of bullets in David Heath’s 1953 “Korea.”

One pairing may be dictated by friendship. Richard Avedon’s famous 1964 portrait of former President Dwight Eisenhower in his 70s hangs next to a 1966 portrait of twins by Avedon’s dear friend Diane Arbus. Even assuming that is the link, only insiders would cotton to it.

In any case, they’re surrounded by photos of children by other artists. So maybe William Eggleston’s “Memphis,” a 1970 color close-up of a tricycle looming large on a driveway, was stuck in as an indirect kid portrait. Or to provide a visual link to Martin Parr’s huge 2012 photo of a bunch of adults and kids in a Minnesota icehouse.

Unanswered questions

By the way: There is a story behind why a British photographer happened to be photographing Minnesotans in an icehouse. Why not tell it? And why not pair Parr’s jolly icehouse crowd with Catherine Opie’s totally different take on Minnesotans’ love affair with winter? Her 2001 picture is a vast expanse of nothingness punctuated by two almost invisible postage-stamp sized shadows: distant icehouses lost in a blizzard. It is hung a long way off, next to a mostly white 1952 nude by Bill Brandt.

A bay of century-spanning portraits ranges from James VanDerZee’s 1908 family snapshot of four well-dressed black guys to Edward S. Curtis’ 1921 bronze-toned photogravure of “A Hopi Man” and Alexander Rodchenko’s memorable 1924 portrait of his friend Osip Brik, whose eye is obscured by the Cyrillic initials of his radical magazine LEF. The portraits include other well-known images by Arnold Newman (Piet Mondrian with his easel), August Sander (a 1945 German soldier) and Minneapolis’ own gonzo photographer, the late Ray Muxter, in a 1973 selfie with Mae West.

The center of the mostly black-and-white portrait group is a huge 2014 color photo by Alec Soth. Called “CF#1,” it is a vast expanse of green turf centered by a small baseball player, back to the camera.

As an ensemble, the 19 portraits are a fascinating sample of a century of portrait styles and important subjects by prominent artists. But nothing guides visitors to draw that conclusion.

Pretty blue paint aside, the show looks like a thrift shop and is about as instructive. Each of these pictures was made by someone, somewhere for some reason. Why not tell visitors a bit about that? Or explain why the museum preserves and shows the images? Or why they’re hung as they are? Surely the curator had some ideas in mind. Why not share them?