"Prosím, pozor" — "Your attention, please." This is the continual background chorus heard by visitors to photographer Antonín Kratochvíl's "Persona" exhibition, a collection of celebrity portraits by the award-winning photojournalist born in Czechoslovakia. That's because the gallery where they are displayed is parked on a platform of a train station. By now the reconstructed set of railroad cars that houses Gallery on the Train has already pulled out of Prague's Hlavní nádraží, and is in Hradec Králové on the second stop on a tour of the country that continues through the summer.

This is the second traveling show organized by the Leica Gallery Prague (LGP), which, after losing its lease at the Burgrave's Palace of Prague Castle, decided to continued its exhibition activities in this itinerant manner. LGP director Jana Bömerová conceived the idea of a "gallery on wheels" as a way to bring major art exhibitions to people who reside outside the cultural centers, and also to exhibit art in a more egalitarian atmosphere.

A peripatetic presentation of Kratochvíl's work seems somehow fitting, considering his own biography. Born in Lovosice in 1947, he spent his youth in Prague and then escaped to Austria in 1967, spending several years in refugee camps before moving to the Netherlands, where he studied art at the Gerrit Rietveltd Art Academy in Amsterdam. From there he emigrated to the United States, first settling in the Los Angeles area and later moving to New York City. He became a U.S. citizen in 1976.

Although Kratochvíl has achieved international recognition, his work was rarely seen in his homeland until he had a major solo show at the National Gallery's Veletržní palác in 2000. Since then, he's had considerably more exposure in the Czech Republic. Last year the Josef Sudek Atelier showed his "Homeland In/Security (USSA)," a look at post-Sept. 11 life in his adopted country. He also had a retrospective in Brno last autumn and is currently part of a three-photographer show called "Prayer for Chernobyl," on view at the St. Jan of Nepomuk Chapel at Our Lady of the Snows Church.

Kratochvíl is best known for his documentary projects, such as the one revisiting the effects of Chernobyl 20 years after the nuclear accident, or a project that took him to Rwanda for three months in 1994.

The black-and-white portraits on display on the train, most taken on assignment for such magazines as Detour, W, Fortune, GQ and Premiere, is a lesser-known thread of his work. In the show's introductory text, photojournalist Michael Perrson writes that Kratochvíl "wants his sitters, alone, on an emotional island."

For these 60 or so images, Kratochvíl adopted a style and method that aims to peel away the mask of his subjects' public personae, and illuminate aspects of their personalities that they may exhibit only in private moments.

There are some excellent photos, including those of Bernardo Bertolucci and Jean Reno. But some lack energy, and others are not very successful in communicating much sense of the subjects.

Considered as a group, there is a tendency toward showing apparent moments of moody solitude or sadness, or portraying the subject looking a bit lost or frightened. Kratochvíl accentuates this with prints that are sometimes grainy, blurred or shot using dim natural light. Several of the sitters cast their eyes downward, or the camera may capture them through a car or café window, which puts them at an additional remove from the viewer/public.