Picasa is free photo editing software from Google that makes your pictures look great.
Sharing your best photos with friends and family is as easy as pressing a button!
Picasa 3.9发布，最主要的新功能就是Google+分享。你可以分享整个相册，只需要点击Share on Google+按钮即可。你也可以单独分享照片，在分享的同时选择要分享到哪个好友圈子。如果你在照片里指认出其中包含有谁，那么在上传到Picasa Web Albums之后，该人的Google+帐号会获得提醒。
除此之外，Picasa 3.9还新增了24个新的照片特效，而且增加了左右对比模式，方便你比对效果处理前后的样式：也许到下一个Picasa 4.0版本，Google就会重命名其为Google Photos了吧？
Added ability to upload to Google+: share with circles, post pictures to your stream, and upload images at original size.
Social Tagging: name tag people in your Google+ circles and notify them via G+.
New photo editing effects, including:
Side by side editing: compare two pictures side-by-side, or compare different edits on the same picture.
Updated RAW support for pictures from newer cameras.
Support for WebP files.
On the Tools > Experimental menu, we’ve added support for migrating your database to another local drive.
Improvements to Face Movie maker: number of photos included, chronological ordering.
Sync now uploads unshared albums privately.
Improved restoring of virtual albums when you uninstall and reinstall, or move to a new computer. Album data is written to the picasa.ini file now, along with all of your other edits.
OAuth support: use 2-factor accounts without getting an application-specific password.