By CAROL VOGEL

Around 1913 Henri Matisse was, in his mid-40s, an international star.

Having returned to Paris from Morocco in the spring of 1913, he began creating paintings that were simpler and more layered than the boldly colorful, sun-filled canvases that had been his signature. The years that followed proved to be a time of enormous change for Matisse. With life in Paris made difficult by World War I, he started experimenting with neutral shades, as well as with geometric shapes and daringly austere compositions.

Although art historians could always track the changes of that period by studying his paintings in progression, one by one, until recently they had no clear idea of exactly how those changes were developed, how much hands-on experimenting went into the new work and what formal processes of study, revision and rejection were involved.

Now those mysteries have been largely solved, thanks to an extraordinary array of technologies deployed in putting together “Matisse: Radical Invention, 1913-1917,” a new exhibition opening this month at the Museum of Modern Art. The show offers a rare opportunity to look beneath the surface of Matisse’s work to see a creative evolution that until now only his eyes had witnessed.

The exhibition’s organizers, John Elderfield, chief curator emeritus at the Museum of Modern Art, and Stephanie d’Alessandro, the curator of modern art at the Art Institute of Chicago, where the exhibit was first shown, focused on 26 paintings, drawings and sculptures. They examined the works with new digital imaging techniques, laser scanning, ultraviolet illumination and up-to-date computer software.

Ms. d’Alessandro and Mr. Elderfield got the idea for the show after they started examining “Bathers by a River,” which Matisse worked on from 1909 to 1916.

After Matisse’s return from Morocco, he started exploring Cubism, which was in full flower with younger artists like Juan Gris, Georges Braque and, of course, Pablo Picasso .

While he admired Cubism for its inventiveness, the more instinctive Matisse was also suspicious of its intellectual emphasis. At the same time he also admired the work of Paul Cezanne as Matisse began to reconsider his own working methods and fundamental ideas about making art.

“Bathers” is a jewel of the Art Institute’s collection. “Matisse said it was one of the most pivotal works in his career,” Ms. D’Alessandro said in an interview. “By studying the painting in depth,” she said, “we began to see a new chronology that hadn’t been seen before, one which explained what he meant by that statement.”

By 1917, Matisse had moved to Nice and re-emerged as another kind of painter, abandoning the Cubist approach and adopting a style closer to Impressionism, painting soft women in cozy interiors as well as smaller, almost romantic canvases, rendered through a harder, more modernist and reductive lens. “He felt he’d done what he set out to do and thought it was crucial to keep changing,” said Mr. Elderfield. “He didn’t want to become a prisoner of that style.”

In examining “Bathers,” the curators could see changes in the outlines of figures beneath the painting’s surface, revealing a constantly shifting landscape of figures. “He kept going back,” Mr. Elderfield said. “Yet he always stopped before a work looked finished.”

The conservators also removed the varnish and previous restorations from “Bathers,” which had yellowed over the years, obscuring the artist’s palette. (They ended up removing the varnish from 20 of the 40 paintings in the show.)

In addition to their work with the paintings, the curators unraveled the steps that had gone into the making of a suite of four largescale relief sculptures depicting the back of a woman inspired in part by “Three Bathers,” a Cezanne painting owned by Matisse. The sculptures, which he began around the time he was working on “Bathers” and developed over 23 years, grew more and more radical over time.

Laser scanning showed exactly how he used a cast from the previous sculpture for each of the works, changing the surface of each succeeding figure until the overall form had a flatter surface and was quite stark and architectural, strikingly similar to many of his paintings during the same period. “Like ‘Bathers’ it’s one conception being evolved over all these years,” Mr. Elderfield said.

Ultimately the curators were able to chart the course of Matisse’s thinking as he added or subtracted details, scraped and rescraped the surface with a knife, moved objects from one side of a canvas to another, sharpened lines - and juggled several works at once, borrowing from one, experimenting with another, never satisfied.

“It really showed us,” Mr. Elderfield said, “what it was like to make these works at this time.”