Channel-surf through the roster of New York TV stations these days and you might catch commercials featuring Denzel Washington’s face on one, Christopher Walken on another and Scarlett Johansson on the next.

But the ads aren’t promoting new movies. They’re pushing Broadway plays.

These days, the tube has increasingly become a go-to medium for producers pushing their straight-play offerings. Successful campaigns for last season’s “Speed-the-Plow” and “God of Carnage” turned legiters’ heads, leading play productions to roll out TV ads earlier and far more often than had been typical. The trend is a notable shift from past seasons, when such commercial buys were mostly for splashy musicals with hefty ad budgets and kinetic dance numbers that translated well to smallscreen campaigns.

A number of factors contribute to the expansion, not least of which is the fact that recent seasons have seen a surge of high-profile actors flocking to the Main Stem, often appearing in limited engagements of nonmusical fare.

“There are plays that are difficult to sell with a TV commercial if you don’t have stars,” says Jeffrey Richards, the frequent play backer who produced “Speed-the-Plow” (starring Jeremy Piven and Elisabeth Moss) along with this season’s “Race” (with James Spader) and the upcoming “Enron,” among others. “But if you have identifiable figures, TV can be very helpful.”

The influx of stars comes coupled with a handful of biz shifts that make TV more affordable for the modest budget of plays, which can average a capitalization cost of $2 million to $3 million vs. the $12 million (at least) likely needed for a sizable musical offering.

Legiters estimate that a TV ad often costs in the range of $10,000 to $20,000 to produce, a sum that includes not only the creation and animation of the images but other expenses such as voiceover talent. Plays can then spend anywhere between $25,000 and $50,000 per week on airtime, with $35,000 pegged as a common figure. (Musicals typically spend about $100,000 per week.)

With the diversification of TV channels has come an increasing ability to target a particular playgoing demo via channels to which they’re likely to gravitate. Along with the usual array of morning shows — “CBS Sunday Morning,” “Today,” “The View,” etc. — advertisers now look to “The Daily Show,” “The Colbert Report,” some offerings on FX and a lot of the programming on Bravo, to name a few examples.

As TV stations have begun to offer more 15-second spots (vs. 30- or 60-second ads), ad-makers have been able to take advantage of those shorter lengths by making moving images out of headshots and graphics for quick, concise segs that probably wouldn’t benefit from more airtime anyway.

With simple video editing and animation capabilities now standard on most laptop computers, ad agencies can get such ads made for less — or even make them themselves. Broadway ad agency SpotCo, for instance, now has an inhouse motion graphics editor.

Every ad puts the greatest prominence on the famous faces involved in a show. Very few, however, reveal much — if anything — about a show’s plot.

“We’re looking for bold graphics, very evocative music and simple, precise copy,” says Nancy Coyne, head of Serino Coyne, the Main Stem ad agency behind spots for “Speed-the-Plow” and “Carnage,” as well as “Race” and the upcoming “Enron.” “We don’t have to do plot. We have to do tone.”

Industry observers agree the first ads to nail the use of TV effectively were “Speed-the-Plow” — which took advantage of the famous-from-TV faces of Piven and Moss — and “Carnage,” toplined by James Gandolfini, best known as a tube mobster.

Both productions saw receipts shoot up after the rollout of the TV campaign; “Speed-the-Plow” went on to recoup despite a high-profile cast upheaval, and “Carnage” became one of the monster hits of last season.

Ads for “Race,” “A Behanding in Spokane” (starring Walken), “A View From the Bridge” (toplined by Johansson and Liev Schreiber) and “Fences” (led by Washington), among others, soon followed suit.

The rise of TV ads for plays also has coincided with the declining effectiveness of print initiatives, which, in a new-media world, often do not carry the weight they once did with prospective theatergoers.

And with a dwindling print budget, more money becomes available for the smallscreen.

“Print dollars are fanning out to a number of places, including TV,” says Tom Greenwald, exec creative director of SpotCo, the agency whose TV ads includes “Fences,” “A View From the Bridge” and “Behanding.” (Advertisers caution, however, that for some plays, particularly those likely to appeal to an older demo, a presence in print is still worth the expense.)

Besides, a TV ad isn’t just for the television nowadays — it’s a video segment that can be used prominently online, too.

“These days, we’re definitely seeing our online buy as an extension of our TV buy,” says SpotCo topper Drew Hodges.

Coyne notes that in general, TV advertising (along with frequent star casting) is one of the factors helping nontuners make it into the black — thereby making plays at least marginally more attractive to legit producers.

“It’s making it a healthier environment on Broadway for plays,” Coyne says.