Basically every image that you see on the web was either created or at least passed through one program: Adobe Photoshop. It’s the main tool for every graphic and web designer out there, the total industry standard. If image editing is something you’re interested in, it should be your first and last stop.
What makes Photoshop the only choice for image manipulation? Well, in addition to the basic stuff like cropping, resizing, and color adjustment, Photoshop gives you the tools to do virtually anything you want with an image. There’s so much to it it can be daunting to novice users; people who have used Photoshop for years still don’t know about every one of its features. However, with an excellent manual and a (relatively) user friendly interface and a little bit of effort, you’ll be doing things you never thought possible in no time. And because Photoshop is basically the only image editor that matters, there are boatloads of books out there to walk you through and get you comfortable with every feature, from the most simple to the most complex.