The 23 frame Panoramic HDR (and how I did it)

As many will know, I enjoy taking Panoramics and HDR though I rarely combine the two and this is why...

First the finished product:


Now the process:

I started with 23 files at 3 different stops (-1EV, 0EV & +1EV) that's 69 files in total, each around 6MB

I first tried to stitch the three stops separately using Photoshop (under automate and photomerge). Boy was this a mistake. If you use Photoshop to merge many files the results are not consistent each time you run it. This meant that no file matched another, which makes HDR practically impossible.

I tried many iterations (each one takes around an hour to process BTW) including:

• reducing the number of originals
• making sure that the files were loaded into Photomerge in the same order (BTW this drastically affects the final result!)

After about 2 days of trying to get something that I could HDR I gave up on this method. I decided to try three new ways of producing the HDR pan

1. Photomerge the 0EV image and produce three images using adjustment layers -- this worked, but not too well:
   
   
   
   
2. Second I tried to HDR one image (Photomatix allows this). Again not much joy:
   
   
   
   
3. Finally I tried the option that was least appealing -- HDR the 23 images separately and then Photomerge. This meant that I would have 23 files around 20MB each.

The third option took a long time, but I think it worked. In the end I had a 12163x6069 pixel HDR Panoramic of Battersea Power station (over a GB in size). After a bit of cropping and compression the final image I now have a 92266x4959 4.6MB file. Here is a slightly smaller version: