The Stanley Basin, near Idaho's famed Sawtooth Mountains, is a forest of mostly lodgepole pines with little undergrowth. In the summer of 2012, droughts, beetles, and lightning strikes caused many of the stands to burn. This is an HDR photo taken a month after the fire, and this article discusses how the photo was made.
HDR is the technique that blends multiple exposures of the same scene into one photograph. When using HDR (High Dynamic Range) you can choose to be subtle, dramatic, or unbelievable. My goal was to be dramatic.
Final Results:
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| Stanley Forest Burn, October 2012 - Click for larger view |
The photo was taken mid-afternoon on a heavily overcast, rainy day, using a grey-card for the main exposure, and white-balanced. Below is the scene, as it appeared "correctly exposed" at EV +0 - no compensation and no editing:
HDR Exposures:
An HDR photograph takes three or more frames, bracketed at various exposure compensation. With software, all are blended and stacked into a final image. Traditionally, take one shot at normal exposure, then a second at +1 stops over-exposure, and another at -1 stops under. HDR combines all three into one picture.
With this, you can pull in shadow and highlights that would be lost to a single exposure. In other words, you do not have to sacrifice shadow detail to capture highlights. The technique can also enhance (and some would say exaggerate) contrasts and colors.
For this photo, I took a sequence of 5 exposures, from -2 stops to +2 stops. All five were combined, building the final image. I made other adjustments to the saturation, hue, and manipulation in the sky:
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| Bracketing Sequence + / - 2 EV - Click for larger view |
Camera-HDR
The exposures can be taken automatically by the camera, using a feature often called auto-bracketing -- letting the camera pick each of the exposures. But my Nikon D5100 is limited with only a three-frame sequence, typically -1 stop EV, 0, +1
stop EV. Software can accept more. Because of this, I bracket manually using Exposure Compensation. Having more frames produces more nuanced results. It is unfortunate that the Nikon does not have a variable setting for the number of frames.
Although many newer cameras can build HDR
exposures in-camera, there is little control. Because of that, I do not use a camera's built-in HDR. If you use the
internal HDR, it does the bracketing for you and, in the case of the
Nikon, only three frames are used.
2017.11 Update: I now am using the camera's auto-bracketing, with the understanding it only supports three exposures. Reason: If there is a wind, and the clouds are moving, I can't capture images fast enough without having artifacts. See this article: Keyliner SwanFalls.
Follow these exposure steps:
1. Be sure the subject, and sky are not moving (wind, fast rivers, most people, etc.). HDR does not tolerate movement during the exposures.
2. You must use a tripod.
3. Set the camera to Aperture-preferred automatic (or manual).
Do not use Program or Shutter-preferred -- you want the depth-of-field to remain constant during all five exposures; do not let the program-mode shift the f-stop.
4. Although not required, shoot RAW (not JPG). RAW for best results. JPG compresses the individual images, causing artifacts.
5. I recommend setting White Balance.
6. Meter the scene with no exposure compensation (EV +0).
I typically use a grey card, but the camera's default meter reading is adequate.
This is what I call the base exposure. Do not take the first picture yet.
7. From the base-exposure,
using exposure compensation, dial-back EV -2 stops, under-exposure.
(For less-dramatic effects, EV -1.5 stops for the first exposure; EV +1.5 for the last)
8. As rapidly as possible, take 5 photos, adjusting the exposure with each picture.
Take the first exposure,
(EV -2). (or EV -1.5 for less dramatic results)
(EV -1), (EV -0.75)
EV +0,
EV+1, and (EV +0.75)
EV +2. (EV + 1.5)
The HDR software does not care about the order, but I keep them in this pattern for reference. Keep the camera rock-steady between shots.
See these Image-Liner articles for details on the Exposure:
Auto-Bracketing vs Exposure Compensation
Using an 18% Grey Card
Controlling White Balance
Moving clouds are particularly troublesome because the bright sky is one of the main reasons for using HDR - the contrast between the sky and foreground can be brought into range. But if they are moving, it causes pixellations and color shifts in the finished HDR
With software trickery, where you can exclude areas from HDR, you will lose the hoped-for dynamic range.
Because they twitch and sway ever-so-slightly, people make poor HDR subjects.
No doubt, shooting JPG at High Quality is convenient, but the images are compressed and will compress more aggressively at the -2 and +2 ranges (blacks and whites are more compressible). For example, look at Frame-1, above. Lots and lots of black. When HDR sees these frames, it will detect more changes than expected and will introduce accidental artifacts into the combined photo. For this reason, shoot RAW.
Post Processing with HDR:
You will need software to process an HDR photo. I use Corel's Paintshop Pro because the software is relatively inexpensive ($90). The remaining steps in this article reference that tool, but other software works similarly.
Organization
Begin by organizing your work.
Create a folder for the image(s). The extra work is worth the trouble, just for the organization of it. The folder contains each of the 5 exposures, the final ".HDR" file, the final printable version, and smaller versions you might send by email or post online. You will likely have 8 to 10 files for one photo. If multiple series of the same subject, give each series its own folder.
It is helpful to rename the five exposures, appending the exposure-compensation in the name. For example, my Nikon named the first exposure as "DSC-0312.NEF". I renamed it as "DSC-0312-2.NEF", where "-2" is two stops under-exposed. Shooting in the same order every time makes this easy.
DSC-0312-2.NEF (-2 stops under-exposed)
DSC-0313-1.NEF (-1 stops under-exposed)
DSC-0314+0.NEF (EV +0 normal exposure)
DSC-0315+1.NEF (+1 stop over-exposed)
DSC-0316+2.NEF (+2 stops over-exposed)
If bracketing at 0.7EV (or other ranges), still use the -2 nomenclature, knowing the real values are stored in the image's EXIF information.
Sometimes when HDRing, I might toss out the +2 frame to bring down the highlights. Renamed files makes this easy to identify.
HDR Steps:
PSP has two modes - "Manage" and "Edit." start in the "Manage" tab to build an HDR.
1. From the Manage tab, click the left-navigation's "Collections/Computer" tabs, changing to "Computer."
2. Browse to the folder created for the HDR
3. On the bottom row, PSP displays thumbnails of the images; this is called the "Organizer." Note exposures (1 through 5). Hover the mouse to see the exposure compensation and the entire filename.
4. Highlight each of the original exposures by clicking the first then shift-click the last (exposures 1 through 5, including +0). The order does not matter, but it is probably sorted by RAW name, under-exposures to over-exposures.
5. Choose the "HDR" Menu.
'Other-mouse-click' any of the images, and choose menu "HDR, Exposure Merge" from the context menu.
If the "HDR" option is greyed or unavailable, you have a previous HDR window open in the background. Minimize PSP and dismiss other open PSP windows.
6. The Left-Navigation shows the initial HDR options, illustrated below,
a. Choose your camera RAW model/brand - e.g. Nikon, Pentax, etc.
b. Choose Feature-based or Edge Alignment (see below)
c. Always choose [x] Auto-crop and
d. Click the "Align" button
* If the resulting image is fuzzy, indistinct, out-of focus, return to this step and
change the Alignment method from 'Feature'-based to 'Edge-detection'.
* I generally ignore the custom editing (auto-brush, brush-in, etc.) on the bottom half.
At the bottom of the navigation panel is a next button.
7. On the next screen, PSP offers six default adjustments.
Generally, the 'Presets' should be ignored because they are usually too strange....
8. ...Instead, scroll to the bottom of the dialog and make changes manually, but if one of the presets is interesting, you could start with it as a base. Often, the horizontal adjustments for Tint and Vibrancy should be adjusted closer to the center than PSP's suggestions.
Adjust until the photo appears as desired.
9. Optional: Create an HDR File.
At the bottom of the left-nav is an optional button, "Create an HDR". This builds a special ".hdr" file that holds all of the exposures and the current slider-settings. Expect the resulting file to be near 100mb if shooting RAW. Use this to re-build or revisit the original HDR settings. I don't consider the file a necessity because the original exposures are still available and can be re-created. The file is convenient if you intend other editing changes or want to play with different styles.
10. Click "Process" on the bottom of the Adjustment navigation panel.
PSP opens another left-nav, allowing for basic photo-editing, such as "Smart Photo Fix". Choose these options as you would for any normal photograph. Consider starting with the Smart Photo fix.
11. Clicking "Finish" opens the merged HDR into a standard Editing window.
Troublesome Touch Ups
All
photos have troublesome areas and it strikes me as humorous when my
mind's eye sees the picture one way but when pulled up on a screen, the
camera captured something different.
Once the HDR has merged and you are presented with a single image, begin your normal darkroom work.
I noted these obvious problems with my photograph:
As usual, I am incapable of leveling a tripod and all the trees lean left. Tilting the frame a few degrees, using the horizon-leveling tool, stood them vertical.
The green stands of trees in the background were not obvious when I took the original pictures. I was pleased when I saw them in the darkroom because they gave hope to an otherwise bleak landscape. These were more emphasized than reality, but I was not after a literal rendition.
Several of the tree's burned bark flaked off, exposing a bright orange bark underneath, much like leopard spots. They were distracting, even in the original photographs. They were calmed in post-processing with some old-fashioned darkroom "burning."
A featureless, flat sky is the bane of all overcast photographs but I recovered with some blatant darkroom trickery -- adding blue that was never there. A dark-blue sky was added to the top-third of the picture, using PSP's graduated filter. This was subtle and I am unapologetic.
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| Click for larger view |
What ever you do, do not fix these problems in the original exposures. You would have to make the
exact change, in the exact same spots in all 5 exposures, which is
impractical and impossible. Make changes after the HDR has
merged.
Final Save - Use Great Caution
With the final, edited image, save the file in your native editor's format (in Paint Shop Pro, they are a '.pspImage" extension). Name this file "something_Final.pspimage". Photoshop users should save as a .PSD / .PSB image.
When saving this image, turn off compression.
For example, PSP compresses its own native file-formats.
In the Save-As menu, click "Options" and turn compression off.
For printing, you want a full-fidelity image and if saved compressed, details will be lost, which can never be recovered. For proof, see this article: JPG Compression. Naturally, an uncompressed image makes for a sizable file -- expect near 100MB per HDR-image.
To share the file, Save-As, and
create smaller versions suitable for websites and email. Name these versions "something_Final_Small800x600.png". Use PNG instead of JPG for better compression. When doing this, take great care in not accidentally overwriting the master files with a "Save".
HDR File Save Recommendations
- Save-As in the editor's native format - e.g., .pspimage, .psd/photoshop
- Name the file "something_Final.pspimage"
- In the Save-As options, turn off all compression
- Save-As a second time and create a "something_Final_Small.png" image for mailing.
- Make no editing changes to any of the original RAW photos
2017.11 Update: A talented photographer-friend of mine thought the colors were too exaggerated (I agree) and he didn't care for the branch sticking up in the center fallen log. I agreed on that too. Here is the most recent edit:
Related articles:
White Balancing
Using an 18% Grey Card
NewPort Bya (Yaquina Bay Bridge)
Highway 21 HDR
JPG Compression
Related Imageliner links:
Jump Creek, Idaho
The Pillars of Rome, Oregon
Frank Church Wilderness, Idaho
Grandview, Idaho
SwanFalls, Idaho
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