Adobe's "Secret" Gift to HDR Users
October 24, 2012
On May 29, 2012, Adobe released Lightroom 4.1. I dutifully upgraded from 4.0, expecting no more than the usual bug fixes and support for new cameras. It was, after all, merely a "decimal point" release. I was quite surprised to learn several months later that Lightroom 4.1 had actually introduced a new feature not found in 4.0: the ability to tone-map 32-bit HDR images. To me, this is huge: you can now process 32-bit images using all of Lightroom's powerful, sophisticated, and familiar controls, with full access to all the information in the 32-bit file, in a completely non-destructive manner. Thirty-two-bit HDR files can cover a much broader range of brightness values than 16-bit raw files. If you shoot in high-contrast light but hate the surreal "HDR" look, Adobe's gift is a breakthrough.
The gift does have a catch. Neither Lightroom 4.1 nor Lightroom 4.3, the latest version as of this writing, have the capability of creating a 32-bit file from your bracketed set of images. For that, you'll need Photoshop CS5 or CS6 or Photomatix. Here's how to use Photoshop: first, go into Lightroom's Preferences (Edit>Preferences) and choose External Editing. In the File Format drop-down menu, choose TIFF. PSD files won't work for this procedure. Then, in Lightroom, select all the images in your bracketed set and choose Photo>Edit In>Merge to HDR Pro in Photoshop. When the Merge to HDR Pro dialog box opens, choose 32 Bit in the Mode drop-down menu. All editing options will disappear. The image may look terrible. Don't worry; just click OK and Photoshop will create the 32-bit file. Again, it may look awful. Save the image. There's no need to change the file name or location. It will appear in your Lightroom catalog right next to the original raw files.
The procedure is a bit different in Photomatix. It's easiest to start in Lightroom. First, select all the images in your bracketed set. Now choose Export>Photomatix Pro. The various settings in the Export dialog box that opens won't actually change our results in this case, so accept the defaults and click Okay. In the next dialog box, be sure "Show intermediary 32-bit image" is checked and click Export. Don't be concerned about the other settings, since we're not interested right now in the 16-bit image. When the 32-bit intermediate image opens, it will look lousy. Choose File>Save As, type in a name or accept the default, then be sure to choose Floating Point TIFF as the file type. You can now close the Photomatix Pro dialog box. There's no need to finish tone-mapping the 32-bit image.
Lightroom may not automatically import the 32-bit file into your catalog even if you check "Automatically re-import into Lightroom Library" in the Settings for Processing Exported Files dialog box. If not, right-click on the folder name in Lightroom where you saved the file and choose Synchronize Folder.
Regardless of the method you use to create the 32-bit file, the next step is the same: open the image in the Develop module. The first thing you'll notice is that the Exposure slider now gives you a plus-or-minus 10-stop range instead of the normal 5. Don't expect to do all the work with the Exposure slider, however. You'll probably need some large adjustments of Shadows, Blacks, Highlights, and Whites to bring out all the detail in the file. Many 32-bit images will benefit from adding contrast in the Tone Curve panel, and you may well need to further adjust shadow and highlight density with the Graduated Filter and Adjustment Brush. You'll find you can recover much more clean, usable detail even in the darkest shadows and brightest highlights than you can from a 16-bit raw file. And it's all non-destructive. You can return to the image at any time to make further refinements. If your goal is to create natural-looking images of high-contrast scenes, you're going to love Adobe's gift.
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