Google Picasa Review - Photo Editing
Picasa lets you edit your photos through various ways. It's similar to popular photo editing tools such as Adobe Photoshop although with less powerful features. Basically Picasa lets you do three types of modifications to your photos- Basic Fixes, Tuning, and Effects.
Basic fixes lets you crop, straighten, remove red eye, retouch blemishes, or add text to your photos. You can even use its auto-fix features through the "I'm Feeling Lucky" all-in-one lighting and contrast fix.
Picasa Effects lets you apply various effects to your photos to make it more interesting. You can use from twelve different effects including sharpen, sepia, black and white, warmify, tint, saturate, film grain, soft focus, focal B&W, filtered B&W, glow, and graduated tint.
Picasa photo tuning lets you adjust the color and lighting aspects of your photo to make it more visually enticing.
You can use all these photo editing tools without the fear of losing your original photos as Picasa saves them and produces a replica that you can work on.