This month at the Palazzo Grassi, looking out over the Grand Canal in Venice, visitors will find a beautiful new floor in the atrium, made of thousands of Italian marble tiles. Only once they’re upstairs, looking down on the entire mosaic, will they see that it depicts a cluster of sparse pine trees. And when they read a wall label, they’ll learn that the evergreens were planted along the border of a Nazi concentration camp, to hide it from public view. The mosaic is the centerpiece of a major retrospective of the Belgian contemporary artist Luc Tuymans, opening at the Palazzo Grassi on March 24 and running through Jan. 6, 2020. It is based on Mr. Tuymans’s 1986 painting “Schwarzheide,” named for a forced-labor camp in Germany where many inmates were worked to death. Mr. Tuymans is credited with bringing painting back in the 1980s, by pioneering a style of figurative painting based on found images. His palette is almost always muted shades of gray, and his forms are blurry and washed-out, suggesting memories of things faded from view. The mosaic may be a departure from his usual medium, but it is also emblematic of his trademark sleight of hand: Mr. Tuymans gives us an image that may make us feel one way, but when we find out what it is — through a title, a wall text, or, in this case, a new perspective — its meaning changes, often in an unsettling way. His work has often reflected on history, in particular World War II and Belgian colonialism, but often concerns current affairs, such as the 9/11 terrorist attacks on the World Trade Center in New York and the war in Iraq. One of his most famous works is a 2005 portrait of the former secretary of state Condoleezza Rice; another is his 1986 “Gas Chamber,” a blanched-out image of an empty space at Dachau. At his Antwerp studio in late January, just before his works were to be picked up for shipment to Venice, Mr. Tuymans smoked cigarette after cigarette and tried to figure out whether the Palazzo Grassi show, with more than 80 paintings plus the mosaic, is his largest to date, out of some 150 solo shows in the last 30 years. Two thirds of the works on display will be recent, from 2016 to 2018, he said. “I made it a point not to show the most topical works,” he said. “This is much more about understatement.” (Some of those the more overtly political works will be shown as part of a retrospective of about 50 paintings at the De Pont museum in Tilburg, the Netherlands, runing from June 29 though Nov. 17.) Bart de Baere, the director of M HKA, the leading contemporary art museum in Antwerp, said Mr. Tuymans doesn’t invent images, but rather repurposes them, and his source material is often drawn from magazines, film stills, Polaroids, internet images and his own iPhone photos. “His primary artistic action is in the choosing of an image,” he said. “Part of that is the awareness of the fact that the image is part of a context and that any choice is partial. No choice is neutral.” The exhibition in Venice is titled “La Pelle” (“The Skin”), a reference to the Italian writer Curzio Malaparte’s 1949 novel, which is set in Naples just after the liberation of that city by the Allied forces at the end of World War II. The novel reflects on how residents of the city have been simultaneously conquered and liberated; they were both co-conspirators and victims of the war.