The latest fatigues were designed with the Middle East in mind, said Dee Townes, a project officer for the Corps' camouflage program.
Scientists assign each color a number called a colormetric and create sample fatigues based on colors that will confuse the eye.
"Camouflage is both a science and an art," said Lt. Col. Gabe Patricio, who managed development of the new Marine fatigues.
Townes said the Marines' new woodland uniform is based on comparisons made of 85 types of camouflage used by hunters.
"We had heard, 'Why can't we have camouflage as good as what hunters can buy for themselves?'" Townes said.
Commercial hunters' camouflage has an advantage over military patterns because it can be designed to blend in with regional terrain and changing seasons.
The woods of Pennsylvania during November's deer hunting season have different colors than the winter terrains in Alaska and Colorado's Rocky Mountains.
"There are a tremendous number of intricate camouflage patterns out there," said Juli Case, a spokeswoman for the Industrial Fabrics Association, which represents the camouflage industry.
"You can find patterns that mimic tree bark or cattails or a forest of evergreens."
But U.S. military camouflage must clothe roughly 212,000 Marines and 480,000 soldiers.
"You can't make 20 different uniforms for every Marine or soldier," Townes said.
Planners have been calling for urban cammies since 1993, when an Army firefight with Somali militia in Mogadishu left 18 Americans dead.
But designers say making a generic urban uniform is almost impossible because cities themselves aren't uniform.
"Think of Miami, with its pinks and bright blues, and think of cities like Chicago and New York that have more gray to them," said Townes. "We're trying to get the urban mission better defined to know where to go with the colors."
The Marines' new cammies will be phased in until every Marine has them in 2006. A spokesman said there's no way to know how many Marines in Iraq have the new uniforms. About 86,000 sets of woodland fatigues and 33,000 sets of desert fatigues have been issued.
The new cammies cost about $60 a set. They're made of a cotton-nylon (permanent press to save dry cleaning costs), and are expected to last about a year.
Grunts are issued a clothing allowance to cover the cost. Officers must buy them out of their salaries.