Adobe Photoshop is expensive. After you have already spent your hard earned cash on a decent DSLR, you are hardly going to be able to afford spending almost the same amount again on software. Photoshop is the best software out there for image manipulation. But luckily, there are free alternatives.
1. GIMP – http://www.gimp.org/downloads/
GIMP is free, image manipulation software. It allows you to do pretty much anything you can with Photoshop. If you are used to the Photoshop interface, it will take some adjusting to get used to the GIMP interface. It is very powerful, and most likely has features you will never use. It works on most platforms, and allows advanced editing techniques using layers etc.
2. Pixlr – http://www.pixlr.com
Pixlr is amazing to me. It is not as feature rich as Photoshop or GIMP, but it does most of the things the average user would need. Where this application astonishes me, is the fact it is completely online! Yep, no downloads. Just browse to the Pixlr website, and start using it. Great for quick edits and fixes, especially when you are not near your usual computer or laptop. As I already mentioned, it is not fully featured, but check it out, I am sure you will be impressed too.
3. Paint.NET – http://www.getpaint.net/
This is a Windows only product. I like the interface better than GIMP, however, it is more limiting than GIMP. Download it and check whether it has the features you require, if it does, it might be just what you are looking for.
4. Picasa – http://picasa.google.com/
Yes, know this isn’t the same as Photoshop. However this is still a very powerful, easy to use application that fulfills the needs of the majority of people. Remove red-eye, increase saturation, increase fill light, straighten the image etc etc etc. A lot of the time, Picasa has everything I need for the changes I want to make. Plus, it is just brilliant at organising, tagging, uploading and backing up all your pictures.
In the same category as Picasa (lightweight image manipulation and photo management), there are two other applications I want to recommend.
5. IrfanView – http://www.irfanview.com/
This is an application I have been using for many years. Primarily it is an image viewing program. It can’t be beat for quick cropping of images, and even has other tools at its disposal (including sharpening, filters etc). It is very handy for batch conversions and renaming.
6. FastStone – http://www.faststone.org/FSViewerDownload.htm
I tried this out for the first time about a year ago. It is very similar in its functionality as IrfanView. The interface is very different, and you will probably choose between Irfanview and FastStone based on the user interface.
Save yourself £500 and try one of the software packages above, I am sure you will find one that suits your needs!