Let night, I got into a quick discussion last night with Tom Hogarty from Adobe about HDR. Yesterday I made a small note in Mason Marsh’s article about Lightroom using a 16-bit HDR file while Aurora, Photomatix, and Photoshop use 32-bit images.

Turns out that’s not a completely fair comparison.  Lightroom uses a 16-bit floating point image while the others use a 32-bit integer image. I’m still digging into the science part fully and hope to have him on a future podcast to nerd out. Here’s the short version.

When you’re using the new Lightroom or Adobe Camera Raw you can now create a HDR raw file.  This is tied to the changes in the DNG (digital negative spec) that allow for floating point processing.  You can see a plain English explanation here — http://blogs.adobe.com/lightroomjournal/2012/10/dng-1-4-specification-notes.html.

While traditional HDR apps (including Photoshop) make a 32-bit file, Lightroom makes a 16-bit float file.  Directly comparing 16-bit float to traditional 32-bit is not that simple.  Float offers extra benefits in how the file is processed and more latitude.  Tom pointed out that the file could maintain up to 30 stops of dynamic range depending on what you feed into it for source files.

So let’s give it a try.

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Merging HDR with Camera Raw

Let’s merge exposures in Camera Raw.  This can be done from Bridge or simply choosing File Open.

1. Select multiple Raw files.  I choose File > Open.

   

2. Select all the images in the Filmstrip viewer.
3. Click the small drop-down menu (it’s kind of hidden) or press Option+M or Alt+M to invoke the Merge to HDR dialog box.
   
4. Use the Align Images option if you had the chance for any movement.
5. Uncheck the Auto Tone option if you’re a control freak like me and want to do this manually.
   
6. Click the Merge button to save the new HDR DNG file.
7.  The file is merged and added to the bottom of the Filmstrip view.
8. Use the controls in Adobe Camera Raw to tone the image to your liking.

   

9. Click the blue text at the bottom of the window and make sure the raw file is set to a Smart Object in Photoshop.

   
   

10. Click Open Object to send to Photoshop.
11. Make any tweaks in Photoshop as you see fit.  In this case I used the clone and patch tools to remove a few distracting elements (AKA other photographers on the workshop who broke the line) and a water tower.

    

12. Export the image using Save for Web or Print as needed.

The Results

I’m quite happy with the results.  I feel I got a very natural looking image that takes advantage of expanded dynamic range.  The 16-bit float file had a lot of information in the highlights that I could recover while shadows are crisp and full.  I’ve been saying it for years… get over your HDR fear and start using these incredible tools.  I still do most of my processing with Photomatix…  but I find that Lightroom and Adobe Photoshop’s ability to keep a raw file throughout is quite appealing and useful.

We’ll explore some of these topics more in future articles, our HDR hangout series, and podcasts.  I hope this helps.

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Filed under: Adobe, HDR, Landscape, Photography, Shooting, Software Tagged: 16-bit float, HDR, HDR learning center, Lightroom, Tom Hogarty