i have been playing with merge to hdr recently and have been encountering a few setbacks. I will not go into elaborate detail here on how to use hdr as instructions for it are all over the place.
For a good tutorial go to
One thing that no one seems to make obvious is how to convert it to a 16 or 8 bit file after you have it saved in a .pbm format. This is easy when you think of it but when you are having trouble to begin with its just one more pain.
After your computer does its magic and you have set the white point slider to where you like it and then hit ok an image appears, magically of course. You then save this file (.pbm extension) and close it. Well you really dont have to close it but i did so you might as well too. Open this file and go to the image menu - mode - and down to 16 or 8 bit. After you choose one and click on it a window will appear which is where you set the mode to local adaptation and adjust the curve.
Now that i've got this far i cant seem to make the image look good using the curve. I will try it again tomorrow. Keep your fingers crossed.