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The Art of HDR Photography Part 4: HDR Workflow

Uwe Steinmueller | Photo Techniques | Published Aug 31, 2011

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.

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

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:

Let's show what we're talking about with examples. 

De-Ghosting with Birds

Sometimes you may see something like this in your final tone-mapped HDR image.
At first it looks like some dust on the sensor. But an inspection of the original photos shows that this was a bird flying through the scene (the sequence was shot at high speed).

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.

Enable de-ghosting. Next we select the area that shows the ghosted elements and make it active.
Mark the ghosted area
Make selection active
We can now see a preview of the de-ghosted image
Obviously this is not the result we wanted. We select the exposure that should define the final result. Here we're using the -4EV exposure for the selection.
Now the preview shows the result we want.

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:

  1. Merge to HDR
  2. Tone-Mapping

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:

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):

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:

We find it much better to launch the image into CS5 in 32 bit mode:

Bit depth selector

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:

Depending on the plugin you use you may get an extra dialog:

Photomatix HDR Express

So which is the best tool for Merge to HDR? We don’t have an answer because all have their strengths:

Tone-Mapping

Although all tone-mapping tools perform the same basic tasks, 

they all produce very different looks. Why? It's all about the handling of what they consider to be 'local' and how they handle edges. All these tools use sophisticated algorithms to attempt to optimize how they deal with edges and how they define 'local' for adding contrast, but they all work differently and as such produce different results. There are no objective criteria to judge the results. It is often simply a matter of your personal preferences. This means that unfortunately we can't save you the work; you'll need to find the tools you like yourself: We just present the alternatives. All tools mentioned here have trial version, so you can experiment and test them with your own images. 

We are also not going into detail about all the different parameters, as this can be found in the product manuals.

Tone-Mapping Tools we use

Photoshop CS5

There are three ways to access Photoshop CS5's tone-mapping:

  1. During the Merge to HDR process. Read our comments why do not recommend this. If you are in a hurry you may save a few clicks though.
     
  2. Converting your image from 32 bit to 16 bit. This always involves a tone-mapping step. 
Mode->16 Bits/Channel

3. Keeping the image in 32 bits and use Image->Adjustments->HDR Toning.

HDR Toning

All these functions allow actually 4 different tone-mapping methods:

CS5 tone-mapping operators

For our purposes only two of them are really relevant.

Exposure and Gamma

We only use Exposure 0 and Gamma 1. This just reduces the bit depth without real tone-mapping.

This method is needed if you want to convert an image to 16 bits but you already did the tone-mapping using other methods (Photoshop HDR toning or with a 3rd party Tone-Mapping plugins).

Local Adaptation

In our opinion this is a quite complex dialog because many of the sliders interact with each other. Once you found some good settings you should save them as a new preset. The Local Adaptation options are beyond the scope of this article; if you want to know more you should check out Photoshop CS5's help files. Most of the time we prefer to use other HDR tools for tone-mapping.

HDRsoft Photomatix

Photomatix Tone-mapping

Photomatix Pro is kind of the 'classic' HDR tool, and some think it produces a distinctive 'Photomatix Look', though these are images processed using Photomatix in a certain way. The Photomatix tone-mapping dialog seems quite complex at first because the settings also interact. Again it is advised to save settings as new presets. Once you start from presets the handling gets much easier. Photomatix's system of presets works very well.

Photomatix has many unique features, such as extensive batch processing and 360 degree panorama support.

There is also a Tone-mapping plugin for CS5 called Tone Mapping that works like Photomatix.

Unified Color HDR Express and Expose

HDR Express

We find the results from HDR Express very good (often looking what some would call “natural”). It is also the easiest to use tool we present. The more advanced tool HDR Expose will likely inherit some of the new features of Express.

HDR Expose

At first glance HDR Expose seems complicated but once you understand the basics it is quite easy to use (read again our tone-mapping principles using HDR Expose in the Dynamic Range chapter.

Unified Color also produces a CS5 plugin “Float 32” that has about the same features as HDR Expose.

Nik Software HDR Efex Pro

HDR Efex Pro

We use HDR Efex Pro mainly as a CS5 plugin. HDR Efex Pro has more options than any other HDR tools, which makes it very powerful but also complex. We use it mainly to create a specific 'look' for our images, and for this we love HDR Efex Pro (see later in this chapter). The preset system in HDR Efex Pro makes this tool more accessible and our advice would be that you explore all the presets first.

Selective tone-mapping

Because Photoshop CS5 allows you to perform multiple different tone-mapping operations on the same HDR image (using the same or even different HDR tools) it is possible to organize these results as layers and blend the results using masks. For our work we only experimented with this option but is can be very useful at times.

Adding a “HDR Look”

Images like this one are often called to have the HDR or Grunge look :

Faded Truck

The interesting point is that the above photo is not a HDR photo; some would call it a 'single photo HDR'. Why is this look associated with HDR? Many HDR photos shown on the web have the following properties:

This look polarizes people. Some love it, and some hate it (calling it 'over-cooked'). We have no firm opinion, as we think it sometimes works for our taste and sometimes it does not. One thing is for sure HDR would be far less popular without this look. All HDR tools can produce such a look from real HDR photos or single shots. The most choices offers Nik Software’s HDR Efex Pro. 

As a consequence we actually split the process into two parts:

In our sample image the look works very well to emphasize the gritty look of rusty and old objects. Grunging a Ferrari may not look that interesting unless you were using it in a more humorous way. It always depends on your vision

Here is another example.

Vintage Airplane

We think this image looks nice and would not need any improvements. We still created a different look in HDR Efex Pro.

Added 'HDR' Look

Does it look better? That's simply not the point. It looks different because we created a different mood. The first version shows the realistic beauty of the plane and the second version looks more like from a fairy-tale. 

Here is our first ever “Grunge” photo and still one we like the most.

Grunged Buik

This is from a real HDR sequence and at its core was created by double tone-mapping in Photomatix Pro. Is it over-cooked? You bet, but that is the whole point. Realistic representation was not our goal (during the editing process we also added some Texture Blending to it).

Post Processing of HDR Images

We hardly ever consider the editing work finished once we have performed the tone-mapping. We just mention the next editing steps without going into the details because these are general editing techniques (the general workflow is covered here). We always work in Photoshop for the final optimization step.

Further learning

This is an edited version of the first chapter of an ongoing work by Uwe Steinmueller of Digital Outback Photo, featuring his personal experiences of HDR photography, and will eventually form the basis of a book on the art of HDR photography. If you'd like to find out more about digital imaging workflow from a fine art photographer's perspective then check out the Digital Outback Photo E-book, 'The Digital Photography Workflow Handbook (2010)', by Uwe Steinmueller and Juergen Gulbins, which covers the complete digital photography workflow from input to output. The 540 page prize-winning handbook covers everything from Import to Print (and even backup) and also features Photoshop and Lightroom techniques, HDR, color management and raw editing.

Also check out our Photoshop processing scripts here.

© 2010, www.dpreview.com & Uwe Steinmueller.