The Art of HDR Photography Part 4: HDR Workflow
Tools we use for our HDR work
There is no single HDR tool that does everything perfectly as you want. We use the following tools for our HDR work and all have their own unique strengths. All the tools talk about in this article work on both Windows and Macs. In many cases the same tools are also available in the form of Photoshop tone-mapping plugins.
- Adobe Lightroom 3.x: Lightroom isn't an HDR tool itself, but we use it as our image raw processor and image organizer. Photoshop is well integrated with Lightroom and the other tools we mention feature Lightroom Export plugins that can be launched from within Lightroom.
- Adobe Photoshop CS5: our main image editing work tool, with full HDR support.
- HDRsoft Photomatix Pro: For many years the best known 3rd-party HDR tool. HDRsoft offers also a plugin called “Tone Mapping”.
- Unified Color HDR Expose or HDR Express: Have received more attention over the last year thanks to the fine "natural looking" results they produce. Their plugin is called Float 32.
- Nik Software HDR Efex Pro: Nik's tool is the newest of these products, but is gaining fans mainly thanks to its rich feature set - and of course the reputation of its other popular plugins (e.g. Silver Efex Pro 2, Viveza). HDR Efex Pro is a plugin for Lightroom and Photoshop.
Note: With the exception of Photoshop, all these HDR tools are also supported by Apple's Aperture image organizer and processor. We don’t have much recent experience with Aperture, as we tend to concentrate on using Lightroom. While Lightroom is available for Mac and Windows, Aperture is Mac only. Most of what we say about the HDR workflow using Lightroom can be applied to using Aperture.
While tools change and improve, the principles really stay the same. That is why in these articles we tend to focus on the essential workflow, independent of the tools used.
Clearly we have our own personal preferences, but this often changes; you'll have to find the tools you think are the best for your own work. All tools we mention have proven to help creating good HDR results.
De-Ghosting is often part of the Merge to HDR process of HDR tools and, as we said before, don’t expect miracles. Here is the strategy we use:
- Try to avoid creating ghosting as much as you can when you're capturing your sequence.
- Some ghosting can easily be fixed in the Raw converter (e.g. Lightroom) before merging
- Try out some of the Merge to HDR tools and see whether they can help. It makes sense to try different tools because they all have different strengths.
- Try to avoid ghosting by selecting different images from your bracketed sequence.
- Try to fix the images before you process them with Merge to HDR.
Let's show what we're talking about with examples.
De-Ghosting with Birds
In the end we treat it as if it was dust. removing the bird from the sky is simple using the healing brush in Photoshop. Removing the bird from the tank requires some clever cloning. Photoshop CS5 made this task a lot easier by introducing the Content Aware Fill function.
|Content-Aware Fill||Cleaned up|
We select the area with the bird (here we used a round selection but a square would be fine too) and use Edit->Fill in Content-Aware mode. The replacement doesn't always work perfectly, but here it is just right.
De-Ghosting with Clouds
Sometimes “Merge to HDR” in Photoshop can create some nasty colors in clouds and sky:
|Merge to HDR in CS5 with "Remove Ghosts" unchecked|
In this case enabling the function Remove ghosts reduced the color fringes, but didn't produce the result we wanted.
|Merge to HDR in CS5 with "Remove Ghosts" checked|
In the end we merged the image to HDR in Photomatix (by HDRsoft) and tone-mapped the 32 bit HDR file using the Float 32 plugin (by Unified Color):
|Improved sky and clouds|
De-Ghosting with Flags
Flags nearly always create ghosting, because they hardly ever stand still. Here is a typical scene:
|Merge to HDR in CS5 with "Remove Ghosts" unchecked|
In this case the Remove ghosts function in Photoshop CS5 does a nice job:
|Merge to HDR in CS5 with "Remove Ghosts" checked (frame 1 selected)|
If Remove ghosts is checked you can select the frame that defines the content used (shown with a green border in the thumbnail list). In this case the first frame was selected.
|Merge to HDR in CS5 with "Remove Ghosts" checked (frame 2 selected)|
De-Ghosting with People
Of course ghosting with people is very common , and can often can be spotted when shooting the bracketed photos.
Let's start with a real world scene and discuss some possible solutions.
|Person walked into the scene|
This scene is kind of special because the person is not in the scene in the first or last shot of the bracketed sequence (at 2 EV steps). What are our options?
Option 1: Retake the pictures
We did in this case. But for the sake of this demonstration we tried to get the best out of this sequence and it worked surprisingly well.
Option 2: Use the de-ghosting features of your HDR software
None of the tools we use could solve the problem in fully automated mode. Both Photoshop and Photomatix worked fine with some user intervention. This is by no means a definitive statement since de-ghosting is very dependent on the images at hand.
Option 3: De-ghosting in CS5
We were quite surprised how well CS5 de-ghosting worked.
|See the ghost in the right part of the frame (Remove ghosts off)|
|Ghost removed (Remove ghosts on, frame 4 selected)|
Option 4: De-Ghosting in Photomatix
Having selected our image sequence in Lightroom we call the Photomatix Export plugin. Here we enable Reduce ghosting artifacts with the sub option Semi-manual.
Option 5: Create an HDR image from the first and last image only.
The first and the last image are 6EV apart. We were very surprised how well it worked using HDR Express.
Option 6: Clone the person out from the two middle exposures
Create TIFF files and clone out the person in the middle two frames:
|Person cloned off|
This method also worked perfectly well.
We cover these options so that you have some methods to choose from. There is no single method that works all of the time.
Merge to HDR
As outlined in an earlier chapter HDR is a two step process:
- Merge to HDR
Merge to HDR is basically a fully automatic process. De-ghosting and alignment are often performed during the Merge to HDR step. We covered alignment and de-ghosting up-front because there are sometimes good reasons not to leave these particular tasks to the automatic Merge to HDR process.
Unfortunately all the different HDR applications deliver different HDR results via their Merge to HDR step (even if we ignore de-ghosting and alignment). The main differences are:
- Colors (mainly saturation)
- Different applications sometimes produce different artifacts
For our personal work we use Photoshop CS5, Photomatix and HDR Express/Expose for different images.
Launch Merge to HDR from Lightroom
We nearly always start from Raw images (highly recommended). We perform some basic and important corrections in Lightroom 3.x (identical for all images in our bracketing sequence):
- Perform highlight recovery if needed
- Lens Correction: mainly we want all CA removed; of course some lens distortion correction is welcome too.
- Noise reduction if needed
- White balance for all images the same
- Keep all tone curves linear
- Black Point to 0
- Basic crop and straighten
Then we select all the photos we want to merge:
|Selected image brackets|
Because Photoshop CS5 is more closely integrated with Lightroom, launching Merge to HDR with the various 3rd party HDR applications differs from using Photoshop.
Merge to HDR in with CS5
With the images selected we select Edit in and then the Merge to HDR Pro in Photoshop menu option.
This will launch Photoshop CS5 and open the images. Note: This operation does not use Lightroom to process the Raw images, but uses Camera Raw directly. This won't matter if you use matching versions of Lightroom and Camera Raw. If not you may be better creating intermediate 16 bit TIFF files.
This may take a while depending on your computer and the size of the images. CS5 also performs an automatic alignment if called from Lightroom. Once CS5 has performed these tasks you'll see the Merge to HDR Pro dialog:
|Merge to HDR Pro dialog|
We covered the Remove ghosts option earlier. You can also directly perform the Tone-mapping here. We advise against it for the following reasons:
- The preview is a downsampled image
- If you want to change tone-mapping settings you cannot got back to this dialog and will have to start over.
If you select 16 or 8 bit (8 is not to be recommended) you can do the tone-mapping directly in this dialog. But as we mentioned we defer it for a later step in CS5.
With the 32 bit image in CS5 you can later perform the same tone-mapping with the Image->Adjustments->HDR Toning function. Then you have the image in full resolution and can even undo the operation.
Merge to HDR in with third party HDR Applications
Third party HDR applications integrate with Lightroom via export plugins. You again select the bracketed frames but this time call the tools via an export plugin:
So which is the best tool for Merge to HDR? We don’t have an answer because all have their strengths:
- CS5: Excellent alignment, good de-ghosting, sometimes artifacts in clouds
- Photomatix: Good alignment, nice de-ghosting
- HDR Express: Colors match well our Raw files, not ideal for aligning handheld photos
- HDR Efex Pro: We hardly used it so far for Merge to HDR. Alignment not as good as in CS5.