If you are looking for powerful yet free online image editors then you will find what you need in the range of services offered by Pixlr. The Pixlr suite offers a comprehensive range of tools and no login is required to use them.
The Pixlr Express service features simple photo editing tools like crop, filter and red eye reduction. There are also a number of borders and filters to edit your picture. The site is an excellent alternative to the popular Picnik editor which will be closing in April.
For more complicated editing tasks, the Pixlr Editor service is very similar to Photoshop. It has a number of high- end editing functions such as layers, filters and brushes. Images can then be saved or uploaded to online services like Facebook, Flickr, or Picasa.
Both services use Flash, so at this stage you can’t use them on an iPad. However, the free Pixlr-o-matic app is available for Android, IOS and in your browser. It allows you to add retro filters to your pictures and share them online.