SAN FRANCISCO — San Francisco may be getting ready to shed its image as a city where anything goes, including clothing.

City lawmakers are scheduled to vote Tuesday on an ordinance that would prohibit nudity in most public places, a blanket ban that represents an escalation of a two-year tiff between a devoted group of men who strut their stuff through the city’s famously gay Castro District and the supervisor who represents the area.

Supervisor Scott Wiener’s proposal would make it illegal for a person over the age of 5 to “expose his or her genitals, perineum or anal region on any public street, sidewalk, street median, parklet or plaza” or while using public transit.

A first offense would carry a maximum penalty of a $100 fine, but prosecutors would have authority to charge a third violation as a misdemeanor punishable by up to a $500 fine and a year in jail. Exemptions would be made for participants at permitted street fairs and parades, such as the city’s annual gay pride event and the Folsom Street Fair, which celebrates sadomasochism and other sexual subcultures.

Wiener said he resisted introducing the ordinance, but felt compelled to act after constituents complained about the naked men who gather in a small Castro plaza most days and sometimes walk the streets au naturel. He persuaded his colleagues last year to pass a law requiring a cloth to be placed between public seating and bare rears, yet the complaints have continued.

“I don’t think having some guys taking their clothes off and hanging out seven days a week at Castro and Market Street is really what San Francisco is about. I think it’s a caricature of what San Francisco is about,” Wiener said.

The proposed ban predictably has produced outrage, as well as a lawsuit. Last week, about two dozen people disrobed in front of City Hall and marched around the block to the amusement of gawking tourists and high school students on a field trip.

Stripped down to his sunglasses and hiking boots, McCray Winpsett, 37, said he understands the disgust of residents who would prefer not to see the body modifications and sex enhancement devices sported by some of the Castro nudists. But he thinks Wiener’s prohibition goes too far in undermining a tradition “that keeps San Francisco weird.”

“A few lewd exhibitionists are really ruining it for the rest of us,” he said. “It’s my time to come out now to present myself in a light and show what true nudity is all about so people can separate the difference between what a nudist is and an exhibitionist is.”

Because clothes are required to enter City Hall itself, demonstrators who try to disrobe at the Board of Supervisors meeting will be escorted out by sheriff’s deputies. That is what happened last Monday when Gypsy Taub removed her dress at a committee hearing where the ban had its first public hearing. Taub, a mother of two, said she got her start as a nudist while hosting a local cable program devoted to the theory that the government was behind the Sept. 11, 2001 terrorist attacks.

“I thought if I take my clothes off, I bet they are going to listen,” she said.

San Francisco lawyer Christina DiEdoardo filed a federal lawsuit last week on behalf of Taub and three men that seeks to block Weiner’s ordinance, if it passes and is signed by Mayor Edwin Lee. The complaint alleges that the ban infringes on the free speech rights of nudists and discriminates against those who cannot afford to obtain a city permit.

While it may seem strange that going out in the buff is not already illegal in San Francisco, most California cities do not have local nudity laws, Wiener said. Instead, they are adequately covered by state indecent exposure laws and societal mores. But indecent exposure technically only applies to lewd behavior, so city officials have had to craft a local solution, he said, adding that the cities of Berkeley and San Jose already have done so.

“I suspect there are a lot of places that maybe don’t currently have a local law (and) that if people started getting naked every day would quickly see a local law,” Wiener said.