Graffiti is any sort of words or drawings, scribbled or painted on a wall or other surface? without permission. That's why most people consider it vandalism. But to others, including photographers Henry Chalfant and Martha Cooper, it's a form of art.  A 1984 book featuring more than 200 of their images of the graffiti on New York City subway cars documented this urban subculture.  Now, a 25th anniversary edition of Subway Art is out with additional photographs.  

When colorful spray-painted names - or tags - started to appear on the sides of New York City's subway cars in the 1970s, they grabbed photographer Henry Chalfant's attention and curiosity.  "I was drawn to the art and to the fact that it was mysterious, done by unknown people for free just putting their artwork up," he says. "I was intrigued."

Another photographer, Martha Cooper, was also intrigued by the images. Both Chalfant and Cooper risked arrest and injury, sneaking into the transit system's train yards and subway tunnels, setting up their cameras on rooftops to capture the early graffiti masterpieces on the trains. The 1984 collection of their photographs, called Subway Art, sold more than half a million copies.

"My pieces are the trains, which are taken out of context, sort of close-up pictures of trains," Chalfant says, "whereas Martha took pictures of the trains in the background of the urban setting. She also took the pictures of people are painting and entering the yards."

The New York City Transit Authority did not appreciate having its trains re-decorated. Defacing public property is illegal, and the city did all it could to stop the graffiti writers and clean up their art. Steve Ogburn, who was only 15 when he started tagging railcars in 1972 using the nickname BLADE, remembers always keeping an eye out for the police.

"Try to imagine being 15 years old, and you're going out with your friends in the middle of the night, 2, 3 in the morning," he says. "You would go to these trains and - just the excitement, the adrenalin rush of painting them! It's exciting! But of course the fear, all the time; you don't want to get arrested, because if you get arrested back in the day, the police are gonna slap you around, and then they're gonna call your parents."

That's why the young graffiti artists were suspicious of Henry Chalfant when he began photographing their work. "They thought that since I was twice their age," he says,"that I was probably a cop, taking pictures as evidence and that I was going to stage an enormous bust as soon as I had them all together."

After a few months, though, he says they started to trust him, and they helped him take better pictures.

"We began to collaborate in a way, because they would tell me when they had painted something, which would give me a great chance to go up and get it and I'd know where to find it," he says. "This was very important because these are ephemeral works of art, they don't last long. The transit authority was cleaning them as fast as they could. Even in the first couple of days, they would probably clean the windows, which would leave holes in the artwork. So the trick was to go out really early and get them while they were fresh."

Chalfant and Martha Cooper captured dozens of colorful sketches, tags and abstract images.  The centerfold of their book features a 1979 work by Steve Ogburn. The huge, almost 3-dimensional letters B-L-A-D-E seem to tumble crazily along the entire length of a subway car.

 "It just looks like the letters would be swinging back and forth," Ogburn says. "They are in all the colors of rainbow like Skittles [candy] and you have these little characters [painted] on the end of the train that are just these little happy characters. And when you did trains back in the 70s, everything was like this upbeat fun thing to do. This was just a way to go out and be teenagers and have fun.

Ogburn says his "Swinging Letter Blade" is the most recognized subway train that was ever painted.

By 1989, though, the graffiti works on New York subway trains were gone. The Metro Transit Authority bought new cars, developed new interior paints and surface materials that were easier to clean, and put heavier security around the rail yards and other sites the taggers had used as their outdoor studios. Eventually, photographer Henry Chalfont says, these young graffiti artists had to move on with their lives.

"There are a number of them who paint as professional artists," he says. "They have collectors. Their work is exhibited in galleries and in some cases, museums. Many others have gone on to become graphic designers and in other related fields. A lot of these young kids started their own magazines and this led them into careers as publishers. In some cases I know some filmmakers who came out of this. Other people perhaps not following their art career, ended up having regular jobs."

Steve Ogburn, 52, is one of those who went on to become a professional artist. His current works -- still in the bold, whimsical style seen on those old subway cars -- sell for thousands of dollars. But he says graffiti is more than just a career for him. It is a life-long passion.   "I still do the original graffiti and I do it on canvas, to promote the way the art form began, back between 1970 and '72, to show the world how it developed originally," he says. "Now, it's caught on, and it's the most copied art form, whether you see it around or you actually see it on commercials and clothing and stuff. It's much more sophisticated now. They have much better techniques than of course what we had, but without the original guy, maybe nothing would have developed at all!"

With the 25th anniversary edition of Subway Art, the artist says, people his age can see more original images and remember those years. The younger generation, he adds, can also enjoy the photographs and may be inspired to invent their own creative - and legal - ways to express themselves.