This time the painting was Monet's The Japanese Footbridge, an impressionist masterpiece depicting lush gardens and a lily pond.
Ronald Sirianni of the Philadelphia Police Crime Scene Unit closed his eyes as instructed and concentrated as other officers fired off details: "Rust-colored water, falling foliage, a weeping willow-type tree . . ."
With that, Sirianni opened his eyes and, though he had never seen the painting, selected it from among two similar Monets.
"The rust-color water was the giveaway," the veteran investigator said proudly.
This curious scene took place not at an art gallery but at the Philadelphia Police Academy as part of "The Art of Perception," a seminar designed to improve police officers' observation and communication skills by teaching them how to analyze works of art.
For six hours Friday, about 40 veteran officers and new detectives sat in a darkened training room in the Northeast, reviewing slide after slide of artworks ranging from Monets to modernists.
Despite Sirianni's good eye, one thing became exceedingly clear: No two people see the same thing the same way.
Or, as Lt. John Bradley put it, "What you see is not always what is."
A danger, of course, in a job all about details small and large, and exactly the point of the seminar, said Amy Herman, the New York art historian who teaches it.
"I am using art as a vehicle for them to step away from their police duties and rethink how we see and perceive and communicate," she said. "I am trying to get them to clean the lenses through which they see their jobs."
In one exercise, Herman showed the class a photograph of a young woman walking along a river near Columbia University. Through the trees in the photo, the letter C was written on a towering rock - which many students missed.
In trying to capture the small details, an observer can miss the bigger picture, she said.
Herman, also a lawyer, started teaching the class 12 years ago while working as the head of education for the Frick Collection in New York City.
At first, she geared the course toward medical students, working to help them become better observers of their patients.
In 2004, she adapted the course to law enforcement and reached out to the New York City Police Department.
"I called them up and said, I have this really great idea," she said. Her call was transferred to a deputy commissioner who agreed, and soon the NYPD adopted Herman's course as part of officer training.
Her inbox exploded, she said, after a 2005 Wall Street Journal article profiled her work with the New York police. She soon quit her museum job and began focusing full-time on the seminar. She now teaches the course to the FBI, the CIA, the Secret Service, and Navy SEALs.
Most law enforcement officers have good perception skills, Herman said. The problem, she said, comes in effectively communicating their perceptions.
Capt. Benjamin Naish arranged for Herman to come Philadelphia after attending her seminar at an FBI National Academy training session in Gettysburg last month.
"I felt like I had my eyes opened wider," he said.
After Police Commissioner Charles H. Ramsey quickly green-lighted the idea, Naish squeezed the seminar into the last day of training for the new detectives, who had just completed five weeks of procedural and computer training.
"This is the most unusual training they're ever going to have a chance to see," Naish said.
The new detectives seemed engaged in the training.
Matt Carey, a six-year veteran newly assigned to Southwest Detectives, was one of many students who missed a mahogany table that blended into the foreground of another painting.
"You have to have soft eyes," said Carey, a former Army Ranger who did three tours overseas.
In another exercise, Herman showed a slide of the surrealist Rene Magritte's Time Transfixed, a painting of an empty fireplace with a locomotive puffing through the middle of it, and complimented those students who described the painting by what it lacked: a fire, candlesticks, tracks for the train.
"When you say what isn't there, you give a more accurate picture of what is there," Herman said.
In another slide, Herman showed a picture of a fat man in tiny shorts sleeping next to his suitcases. Students tossed out scenarios: The man had been evicted, or was sleeping off a drunk in the hallway. In reality, the sleeping man was not a man at all but a lifelike sculpture installed in an Orlando airport.
"You can have the best observation and perception skills in the world, and sometimes you're just going to be dead wrong," Herman said as the students nodded in agreement. "You need to accept it, learn from it, and move on."