Menlo Park, Calif. - Facebook announced Thursday a substantial redesign of its News Feed, the front page that users see when they access the service.

Mark Zuckerberg described the new News Feed as a "personalized newspaper" that is more visual and allows users to choose the topics they're most interested in. The images and links to articles are bigger, making it easier to see on mobile screens.

"This design reflects the evolving face of News Feed," Zuckerberg said at a news conference at the company's headquarters in Silicon Valley.

The redesign does not change anything about the filtering algorithm that Facebook uses to select what shows up on a user's News Feed.

But users will now be able to drill down into topic-specific news feeds - one for music, another for photos, another for the publications, celebrities or brands they follow. That choice is aimed at addressing a concern raised by advertisers and content publishers such as news sites: Under the old system, it was difficult for their followers to see everything the companies had posted.

The redesigned News Feed was clearly inspired by the ubiquity of cellphones, particularly in how easy they make taking and sharing photos online. Zuckerberg said half of all posts on the News Feed now are pictures, up from 25 percent a year ago. The pictures will show up bigger in the new feed.

Facebook executives did not directly respond to whether this would mean more advertisements in the News Feed, but the redesign stands to benefit advertisers because the space for ads is bigger.

Julie Zhou, head of design at the company, also said advertising formats would become more visual. "Everything across the board is going to get this richer, more immersive design," Zhou said.

Facebook said it would begin rolling out the changes to the Web version immediately, with mobile apps to follow.

The makeover is aimed at both keeping users glued to the social network and luring more advertising dollars.

But they also reflect the tricky balance Facebook faces now that it is a public company: to keep drawing users to the site while not alienating them with more finely targeted advertisements, which is Facebook's chief source of revenue.

The pressures are acute, given Facebook's still anemic performance on Wall Street. It came out of the box in May with an extraordinarily high valuation of $38 a share, which slumped to half last fall and has remained for the most part under $30. In midday trading Thursday, the stock was about $28 a share.

The social networking giant has tweaked its News Feed over the years. Since 2009, Facebook has filtered what every user sees on the News Feed, based on the wisdom of its proprietary algorithm, called Edge Rank, which determines which posts a particular user is likely to find most interesting.

In 2010, it allowed users to filter the contents of the scrolling feed chronologically. The next year, it introduced a separate right-hand-side ticker - Twitter-esque, some said - of everything that every "friend" and brand page had posted.