There's nothing flashy about "Sunrise Earth," a show that airs weekday mornings on Discovery HD Theater. The program simply captures a sunrise, with no narration, no music, no host. What's special about it is that it's captured in vivid high definition. And for an increasing number of viewers, that's enough.

In the past few months, consumers have found new reasons to upgrade their television-viewing experience. The number of channels broadcasting in HD are on the rise, spurred by the drastic drop in price of high-definition TV sets. Plasma screens priced near $4,000 three years ago now go for about $1,500.

Today, 26 percent of U.S. households are watching sets that offer higher-resolution pictures, according to the Consumer Electronics Association in Arlington, Va. HD sets being shipped in the United States are expected to more than double by 2010.

With more viewers comes increased pressure to make more channels available in high definition. The average cable subscriber receives fewer than a dozen channels that can broadcast in high definition, and then not every show on each channel is produced in the higher-quality format. But that's changing, as the rollout of more HD channels and shows becomes one of the priorities for the studios, as well as cable and satellite providers. DirecTV, for example, has pledged to offer 100 HD channels by the end of the year.

Like the introduction of color TV in the 1960s and cable TV in the late 1970s, the shift to the new format will transform mainstream television viewing. The improved quality comes with a higher price tag, however, not just for those buying the sets, but also for those making and transmitting the programs.

"People want to justify their expense," said Phillip Swann, president and chief executive of Virginia-based TVPredictions .com. "They're sitting around saying, 'I've got to watch something in high-def because I just spent $2,000 on a high-def TV.' "

The leader in high-definition channel offerings today is Dish Network, with more than 30. DirecTV and Dish Network plan to add channels later this year and early next year, including offerings from ESPN, ABC Family, the History Channel and the Disney Channel.

For networks, especially those with numerous niche channels under their umbrellas, the payback is becoming more evident. Discovery Communications, for example, has noted that viewers are tuning in to the five-year-old Discovery HD Theater to watch shows like "Sunrise Earth" and "Deadliest Catch," a show about Alaskan crab fishermen that they otherwise might never have discovered, said Clint Stinchcomb, executive vice president for the HD network at Discovery.

Ratings are carrying over to Discovery's other standard-definition channels after segments from those channels appear on Discovery HD Theater, he said, pointing to a boost at "Animal Planet" after one show was on the theater channel.

Viewers who experience television in high-definition tend to stick with it, he said. It's hard for them to go back to regular old programming.

"What that enabled us to do ... was to develop a deep emotional connection with the 11 (million) to 12 million who are able to access the service today," Stinchcomb said.

But as the number of channels offering HD shows increases, so does the strain being put on the technology that delivers those shows to viewers. The number of channels that a cable or satellite provider can offer on its lineup is limited by the amount of programming transmitted to set-top boxes at any given moment. High-definition programming, because of the amount of data needed to create the higher quality, eats up six to seven times the amount of capacity of standard programming.

To increase capacities, DirecTV and Dish Network are launching more satellites. DirecTV said the first of two satellites is scheduled to be launched next month and the other later in the year, a timetable that is critical to ensuring that it can deliver on its 100-channel promise. DishNetwork's parent company, EchoStar, has said it plans to launch two satellites before the end of the year.

"We will continue to supply as much HD as is possible," EchoStar spokeswoman Cory Vasquez said, noting that the company would have the capacity to offer as many as 200 HD channels nationally next year.

The cable industry, meanwhile, is developing its own technology to help it deal with increased demands on its system.

Comcast is set to begin testing a technology called Digital Switch Video that helps it preserve capacity. Instead of delivering all channels to all subscribers simultaneously, the technology would send the channel as the viewer tunes into it. Until that technology is widely available, Comcast is trying to sell consumers its On-Demand service, which allows users to pull up a listing of high-definition programs without taxing the network.

Over time, consumers will be able to find high-definition content from many sources, not just cable, satellite or over-the-air high-definition signals broadcast by traditional networks.

As video programming over the Internet also expands, consumers will be able to see Web-based content on their HDTV screens. AppleTV, introduced this year, allows users to wirelessly transmit movies and television shows downloaded from iTunes. High-definition DVDs, while still limited in their selection, are made for the higher-resolution screen.