Google has added an online photo-sharing feature to Picasa, the free software that lets users organise digital photos on their computers.

The test Picasa Web Albums offering is available by invitation only and appears similar to popular photo sharing website Flickr.

Users of Picasa Web Albums can upload photos from the Picasa software program to a web page and create galleries there. A “share” button lets users email links to individual photos, albums or galleries to friends. A “my favorites” tab allows users to list links to friends' Web Albums.

Interested users must have a Gmail account and sign up to be invited to try the service. Google will offer invitations on a first come, first serve basis.

Once invited, a user needs the latest version of Picasa software, which is available to download for free.

Web Albums users get 250MB of free storage or can pay $25 to get an additional 6GB of storage. For now, Web Albums is available in English only.

Google didn't specify how long the test would last, saying only that it hopes to make Web Albums more broadly available soon.

Flickr, the popular photo-sharing service that is now owned by Yahoo and has been available for a couple years, offers a $25 yearly subscription that includes unlimited storage space but a cap on how much users can upload each month. Flickr users can upload photos from mobile phones as well as computers.

Google bought Picasa in 2004.