SAN FRANCISCO - The U.S. online-advertising market is expected to top $30 billion in value this year, while chipping away at the considerably larger pool of money still being drawn in by the stodgier, more-established medium of television.

That's helped focus the attention of Google Inc., Comcast Corp. and others to better automate and broker the sort of targeted ads already prevalent online for the traditional medium's channels. It's also helped attract smaller upstarts sensing a profound change in the TV industry.

Among these small firms is closely held Spot Runner Inc., which is backed by more than $100 million from a broad range of investors, including CBS Corp., and advertising giant WPP Group PLC.

According to data from the Interactive Advertising Bureau, online-advertising revenue in the United States reached $21.2 billion in 2007. Total advertising revenue for cable and broadcast television, meanwhile, topped $40 billion in 2007, the IAB reports.

But many see online advertising weathering the current downturn in the economy, and eating into TV advertising's lead in revenue, as more companies seek out the sort of targeted and easily tracked campaigns available on the Web. Research firm IDC said that it expects the threat of recession will decrease advertising expenditure across all media by as much as 7 percent this year, while online advertising should see quarterly growth between 15 percent and 20 percent over the same period.

Companies trying to help television retain and expand its ad revenue by tapping Internet technology face considerable challenges, though. That's because they'll be attempting to disrupt the formidable TV-advertising industry with automation, while threatening to flatten prices through increased efficiency.

"There are some institutional barriers to dominating the television market," said Forrester Research analyst David Graves.

Google's TV Ads program, opened to the public in April, aims to replicate the search titan's automated-auction formula by taking online bids for spots based on keywords to run in certain shows and at certain times. Google's technology, placed in set-top boxes provided to customers of partner Dish Network Corp., is designed to gather and report details such as when viewers prematurely tuned out of a particular advertisement, and when they stayed put for its entirety.

Meanwhile Canoe Ventures, a newly announced joint effort between Comcast, Charter Communications Inc., Cablevision Systems Corp., Time Warner Cable and others, plans to deploy similar set-top box technology in "a few years," according to Canoe Ventures Chief Executive David Verklin.

Unlike Google's TV-ad program, however, Canoe Ventures will not seek to automate the sale of an ad with an auction, instead pitching its technology to existing sales teams at individual networks. The effort is backed by an initial $150 million investment, and Verklin will officially assume the chief executive role in August.

The move toward applying Internet tools to TV advertising also has lured fledgling enterprises. Los Angeles-based Spot Runner, for example, has carved a niche as a provider of an online system to help businesses create and run ads tailored for local markets.

Launched in 2006, Spot Runner provides an in-house creative staff that helps businesses assemble ads from scratch and select airtime for them on specific networks via the Web.

The startup has stirred a great deal of speculation that it will be acquired by one of the larger players aggressively seeking to build out their own advertising services, such as Microsoft Corp..

"We're talking to everyone all the time, but we don't comment on the rumors," said Spot Runner President John Gentry.

The high hopes for Spot Runner are evidenced by its long list of investors, which includes CBS, WPP Group and Legg Mason Inc., a large institutional firm that has only invested a total of six other startups backed by venture capital, according to data from Dow Jones VentureSource.

Investors also include Lachlan Murdoch, son of News Corp. Chairman Rupert Murdoch. (News Corp. is the owner of MarketWatch, publisher of this report.)

Spot Runner, like Canoe Ventures, also doesn't go as far as Google by offering an auction process to finalize prices. "It's far less disruptive than that," Gentry said.

Forrester's Graves said that by positioning itself as less of a threat to the traditional advertising industry may work in the startup's favor. "People who buy television feel there's a more complex decision process than an auction process will support. These people make their living by claiming they add value you wouldn't get with an auction system."

Michael Steib, director of Google TV Ads, said that the auction process is simply meant to help expand efficient ad sales to "niche" channels that don't receive the same audience measurement offered for more prominent channels - while drawing in advertisers who previously may have shied away from TV.

"We believe you can apply computer science to an industry like television," he added.

What's more, fears that Internet systems such as Google's auction process will depress TV-advertising prices are misguided, according to Steib. "What the auction will yield is the market price, and that's pretty much what people are already paying."

Google's TV Ads service shouldn't be seen as a direct competitor to Spot Runner or Canoe Ventures, he said, because of its distinct approach. While Steib acknowledged that "it takes a while" to convince companies to make use of such technology, he described the results so far as encouraging.

Google is looking to expand beyond its partnership with Dish Network, Steib said, which limits the service to the network's roughly 14 million subscribers.

Verklin of Canoe Ventures said that one of the group's initial goals will be training individual networks in the use of its technology, while at the same time attempting to mesh the various operations of its disparate members. "The challenges we face are enormous," he commented.

But the advantages for networks using Canoe Ventures' technology, Verklin elaborated, could be a more efficient use of air time - so that, for example, a person without a pet won't be subjected to a pet-food commercial. "We're going to take some of ESPN's spots if they so desire and carve those up into the best possible demographic and product usage slices," he said.

Yet initially Canoe Ventures will focus on an interactive product that will let TV viewers respond to ads by making purchases or requesting more information, according to Verklin. That product should be out in the next 18 months.

"We're trying to bring some new energy" to the TV-advertising business, he remarked.

While Comcast Chief Operating Officer Steve Burke told analysts during its fourth-quarter conference call in February that it plans to spend between $50 million and $70 million on "interactive-advertising infrastructure," a Comcast spokeswoman declined to say how much of that has been allotted to Canoe Ventures.