Anyone familiar with modern photography, even simple magazine image appreciation, has seen HDR (high dynamic range) images. Various shooting and processing techniques push the boundaries of “regular” processing and can create surrealistic imagery. This works effectively, or horribly, depending on taste, for many urban settings, such as dark alleyways, people images with striking fashion choices, or metallic imagery, especially of vehicles. However, this over-processed look rarely suits traditional landscape subjects well. Yet, many landscape images could benefit greatly from widened tonal range available only through image bracketing and some method of dynamic processing. Enter 32-bit file processing!
32 Bit file processing widens the available working dynamic range while maintaining the ability to produce photorealistic images, making it the perfect solution for landscape images!
Before one can hope to utilize this editing strategy, you must tailor your shooting to maximize captured data capture and optimize image quality for file merging.
- Shoot in RAW – all the time.
- Bracket shots – at least 2 stops (3-5 images), 3-4 stops are better (7-9 images).
- Use a tripod
There are entire articles and book chapters dedicated to the debate about JPEG vs. RAW files – in short, RAW is always the better option for landscape shots. RAW files are much larger and require post-processing than JPEG, but the data captured, and thus the ability to post-process, far outweighs that trade-off. Further, with digital memory being free, there is little reason not to bracket landscape shots. A minimum of 2 stops (5 shots on Nikon) is good, and frequently 7-9 captures will yield the best results. Finally the best landscape images will always come from a tripod – even in decent lighting, to lock down framing and provide maximal camera stabilization for crisp focus.
There are numerous blogs and videos available on the 32 bit process. I became aware of the technique through reading an article by William Neill, “Natural HDR” from June 2013 Outdoor Photographer, pp.30-33.
I also found this video walk-through particularly helpful:
Lightroom 4.1 or later can recognize 32 bit files. I have used Lightroom 4 (now 5) and Photoshop CS6 for my workflow, although there are many other software options to work with. Adobe Camera Raw will also work with 32 bit files.
The conversion process is straightforward:
1. Highlight images, go under “edit in” heading, choose “Merge to HDR Pro in Photoshop”
2. Files will eventually open in Photoshop in the HDR panel. In the upper right area of the panel you will see “Mode” – this will default to 16 bit. Simply change this to “32 bit” and click “OK.”
3. Now in Photoshop, “save as” a 32 bit tiff file with no compression.
4. Now reload this image in Lightroom (or Adobe Camera Raw).
As you can see, the initial 32 bit files look TERRIBLE on the screen, because the computer does not have the capacity to display it effectively. Thus, your image will inevitably initially appear worse than it did prior to processing. Don’t fret about this; the 32 bit file is merely a means to make available the wider dynamic range for final processing. This file will soon begin to take shape as you process your image.
Once you get back into Lightroom, the true advantages and magic of the 32-bit file will begin to show themselves. First of all when you look at the exposure slider you’ll see that you have 10 stops of tonal range at your disposal!
How you proceed from this point is a matter of opinion and taste, and a quick search on the Internet will show you multiple different ways to follow. I have found the following strategy the best way to proceed.
I first set the exposure so that the histogram is well balanced, generally in the middle with a slight right shift. Second, I reduce highlights as much as needed, often all the way down to -100. Third I increased the shadows as much as needed, often all the way to +100. Fourth, I widen my histogram as much as possible so that I can have as much tonal range available. This means pushing the white slider to the right (plus), well below the point of clipping the highlights but enough to expand the range, and moving the blacks lighter to the left (minus), again avoiding clipping anything unless it is artistically desirable.
This round of edits should get your photo into good working order. From this point you can proceed with your regular stylistic edits, including Clarity, Vibrance, Tone Curve, and Sharpness, plus contrast and any color curve edits you would otherwise make. This may be the end of your editing work.
However, if you find that your image still needs Tonality control, especially in Highlights or Shadows, this is the moment where the 32 bit file really stands out.
If more tonal range control is needed, simply export this edit version as a tiff file (now a 16-bit file), and then re-upload that image, and start all over again with full tonal range!
I have also experimented with 32 bit processing for images where tonal range was not problematic. In some instances there was no benefit; however, I found that some really “popped” after this processing – you may want to give it a try as well.
So, the next time you are faced with a tonal challenge, make the necessary alterations to your shooting style to allow for 32 bit processing once home – you’ll be glad you did!