Photoshop :: Creating HDR Images From One Source Image

I know it might sound weird, HDR images are usually built from multiple images all taken from the same place at the same time but using different exposures.

I'd like to create a HDR image from multiple versions of one source image. I have a number of pictures where I've taken the photo exposing for the sky. This resulted in the landscape/buildings being darker than desired usually. These areas can be easily brightened up though. I find that if I expose for the landscape and buildings, then the sky is washed out and unrecoverable. If I expose for the sky, the landscape and buildings are merely "a bit dark" and can be recovered simply by adjusting the brightness/contrast in photoshop. Of course doing this washes out the sky again, so I need to create a composite of good sky and brightened landscape and buildings. I'm not creating anything professional, so it's not important that I use the best pro techniques.

What I've traditionally done is have two layers, one with the original image (with the good sky) and one with the lightened image (with the good landscape and buildings) and using a mask for the sky, I can put the good (unlightened) sky on the lightened image. Standard stuff really.

So when I heard about HDR automation, I'd hoped that I could take my original image (with the good sky), take a second lightened version of the very same image, put it on a layer, select a HDR automation tool and have it somehow merge them magically. When I've tried this though, nothing seems to happen. I'm left with an unmerged image. I'm pretty sure I'm going about it wrong.

I wonder whether this HDR automation isn't going to help me and perhaps my fake pseudo HDR image creation technique is worth sticking with.

I've been using Corel Photopaint 8 for many years and only just switched to PS CS3 recently (mostly driven by the thought of this cool HDR feature). I'm still finding my way a bit. I'm using it on XP if that makes a difference.