What are the free HDR programs available for download?
- I want to know the cheapest method to perform HDR with the cheapest non-professional camera.
- List of softwares.
As far as cameras go, the only feature that you need your camera to have to take HDR pictures is exposure compensation. It is nice if the camera can do exposure bracketing as well, but it isn't strictly necessary, since you can change the exposure manually between shots.
The HDR method involves taking several pictures with different exposure compensations. The simplest setup is to take three pictures, the first with exposure compensation set to 0, and the next two with exposure compensation at plus and minus some value, which you will choose depending on how much contrast there is in your scene. Typically doing 0/+2/-2 stops is a good place to start. Of course you can opt to take more than three pictures, for example, you can do five at 0/+1/-1/+2/-2 stops.
If you plan on using a low end point & shoot camera from Canon, then chances are that you can install CHDK on it. CHDK enhances the camera firmware with many useful functions that aren't provided by the manufacturer's firmware, including auto bracketing for HDR.
For processing HDR pictures I can recommend the free and open source Luminance HDR. This is a pretty good package with many options. You may want to Google for tutorials that show the most common processing settings to use.
Another option, if you don't care so much about getting the HDR "look" but instead want to generate a normal looking picture with an enhanced dynamic range, then Enfuse is a good option. This tool does not technically do HDR processing, it just takes all the pictures at different exposures and blends them together using a "local contrast" algorithm. But the results are pretty good.