Twitter said Tuesday it overhauled its user display to make the messaging service "more visual," as it ramps up competition against photo-sharing services like Instagram.

"So many of the great moments you share on Twitter are made even better with photos or with videos from Vine," Twitter's Michael Sippey said in a blog post.

"These rich tweets can bring your followers closer to what's happening, and make them feel like they are right there with you."

Sippey said that "starting today, timelines on Twitter will be more visual and more engaging: previews of Twitter photos and videos from Vine will be front and center in tweets."

Some Twitter users noticed the change, which makes pictures, graphics and videos more prominent.

The company said it was incorporating the changes in Twitter on the Internet and its Android and iPhone apps.

The shift comes as Twitter is preparing its stock market debut, possibly as early as next week.

While Twitter has amassed more than 200 million users and a strong core of celebrities, journalists and political leaders, some critics say the service lacks the visual appeal of photo-centric services like Pinterest or Instagram, which was acquired by Facebook last year.

Twitter is seeking to raise some $1.6 billion in its IPO, valuing the company in the range of $9.3 billion and $11.1 billion.

Google+ adds photo, video tools to ramp up challenge

Also on Tuesday, Google+ added "auto-amazing" photo and video tools for telling artful life stories at the online social network, ramping up its challenge to Facebook.

"Google aims to revolutionize photography," Google senior vice president Vic Gundotra said while introducing a host of new social networking features at an art gallery in San Francisco.

Photo and video sharing are among prime uses of online social networks. Gundotra said that Google+ users upload about 1.5 billion images weekly.

He also announced the that number of people who use Google's two-year-old social network at least once a month has climbed to 540 million from about 300 million early this year.

Facebook still dominates the world of online social networking, boasting more than a billion users.

Google hoped to bolster the popularity of its social network with the addition of photo and video editing tools that automatically provide users with professional quality images and custom-made movies.

Tools for automatically editing images and even creating mini-animated sequences of images or moment-capturing action shots were added.

An "auto-awesome eraser" feature allow Google+ users to make unwanted people or objects in images disappear.

Google also beefed up search image search capabilities, increasing the number of terms that can be used to find specific pictures.

The list of a thousand new terms included snow, beach, kiss, hug and sunset. Searches for such terms find pictures with the objects, people or actions even if they are not tagged with caption information.

"You can say the name of your loved one, at the beach, with sunglasses, and Google+ will bring up that image," Gundotra said.

The power of Google's data centers and software were also aimed at videos uploaded to the social network.

Video tools offered to automatically analyze video clips and images, and then weave them into movies complete with synched music sound tracks.

"Google+ has created an auto-awesome movie for you," Gundotra said while showing off new features.

"This is not some little client editing system; this is the power of Google machine learning applied to photos and videos."

Google+ also unveiled improvements to its "hangouts" features that let people video conference free at the social network.

For example, organizers of hangouts can oust unwanted participants or turn up the volume on others.

"We are not building a service for lightweight sharing," Gundotra said.

"We are building a service where you can trust Google with the full resolution of your memories. And we are just getting started."