I’ve been creating images for a long time now and one of the things I’ve come to appreciate is the importance of post processing. There’s more than one way to process a digital image and there’s no one result that is always the right one. When we share our pictures with others they represent our own unique vision of an image (our photographic style) and I’ve used post processing on all of my images to create my own “signature style” of photography.
I’ve changed my thinking about what my final images should look a number of times over the years. And if there’s one form of photography where my post-processing has evolved the most it’s HDR photography. In this blog entry I want to talk about how I can take a single set of images and use them to create three or four different looks. Once I have a few options I can choose the best one or I can use layers, blend modes and masks to combine what I like most about different versions into a single final image.
The Starting Images
All of my tone-mapped HDR images begin with a bracketed set of shots. It can be as few as 3 images spaced two to three stops apart in exposure or it can be as many as 20 images each less than a stop apart in exposure. I’ve had considerably more success creating 32 bit images when I have 10 or more images to work with but 3 shot bracketed sets work best for me when I can’t use a tripod. Today I’ll be working with three images of a F-4 Phantom that I shot at the Air & Space Museum in Chantilly, VA. Here’s a look at three images that were taken 2 stops apart:
The ideal way to capture a bracketed set of images is to use a tripod and set your camera to a low ISO and an aperture around f8. Unfortunately you can’t always use a tripod (like in the Smithsonian Air & Space Museum) so you have to do what you can to capture your shots with as little movement as possible. To keep motion blur to a minimum it’s best to use the fastest shutter speeds you can.
To capture the three images of the F-4S I began by setting my camera to Aperture Priority mode and choosing f4. If you think I was purposely being ironic by shooting the F-4 with an aperture setting of f4 it wasn’t actually that simple. I was looking for a large enough aperture setting to keep my shutter speed reasonable without being wide open (f2.8 is wide open on the lens I used). At f4 I had good sharpness and my shutter speed stayed below 1/30th of a second (important because I had to capture these images without a tripod). If f4 didn’t work for me I would have increased my aperture all the way to f2.8.
To get the fastest shutter speed I could my camera sensitivity was set to ISO 1600. I’ll be the first to admit that this is a little high for my camera (although it might look killer on other cameras). Personally I don’t worry much about the added noise from using a high ISO since I can manage the noise with Lightroom or Photoshop.
I then set the camera to shoot a three shot continuous bracketed set (meaning the camera quickly took three shots with a single shutter release press). I chose a 2 stop differential between shots and then used exposure compensation to set my middle exposure down one stop. The resulting set gave me good exposure for the light coming in from the windows (in the -3EV shot), a good look into the shadows (in the +1EV shot) and a middle exposure shot to help Photoshop bring it all together.
With my camera settings locked in it was then just a matter of finding a composition I liked and patiently waiting for everyone to move out of my shot. Here’s a look at my three images of the F-4s Phantom II put together:
Processing a Single Image (no HDR processing)
After I finished my visit to the museum I returned home to began the long process of offloading the files (including backing them up, adding metadata tags and importing them into Lightroom). When all of my transferring is complete I can begin to evaluate the shots and begin processing the RAW files.
Before I commit to a full HDR processing I like to begin by taking a middle exposure shot and working it the same way I would work any image. I’ll do a lens correction, white balance adjustment, exposure correction (working with the exposure, highlight and shadow sliders), noise removal, adding color (increasing the vibrance), working with the midrange contrast (increasing the clarity slider) and then sharpening the image. Most of these moves have already been saved as a preset so to save time I’ll run my preset and then fine tune the result.
At that point I’ll move the image over to Photoshop to do a little fine tuning like removing any distractions from the shot with the clone stamp tool. Here’s a look at the middle exposure image after I did my typical single shot post-processing:
It’s not a bad shot and I could just stop right here. But I happen to think I could make it a little more exciting. I also noticed that it suffers from a pink/yellow color cast (especially on the F-4S). The color cast isn’t a big deal to me since I can eliminate it pretty easily in Photoshop. After looking at the finished image I was inspired to create something more exciting and I knew I had two more exposures handy for creating a 32 bit HDR. Instead of spending a bunch of time removing the color casts I decided to stop working on this version of the F-4S image and save it as a jpg file (in case I needed to blend it with another shot later).
It was time to take my three exposures and bring them together into a single 32bit HDR image.
Before I continue I’d like to say that there are plenty of very good HDR programs out there including Nik HDR Efex Pro and Photomatix. I’ve used both and they’re both great. But these days I use Lightroom 4 and Photoshop for almost everything so I just find it easier to do my HDR work in them. For this blog entry (and part 2) I’ll only be using LIghtroom and Photoshop to create my 32 bit files and tone-mapping. Remember, I’m not saying this is the only way or the right way to create HDR images, only the way I’m creating HDR images.
HDR Processing with Photoshop HDR Pro
At this point I return to Lightroom where I reset the image I just processed (there’s a reset button that makes this super easy). Then I selected my three bracketed shots by clicking the first image then holding down the shift button when I click the last image. With the three shots selected I chose the middle exposure shot to work on. I perform a lens correction and a white balance adjustment before I address noise and sharpness. At this stage I like to add some vibrance and clarity to the shot (but not too much). Because I’m going to combine the three shots into a single 32 bit file I don’t spend a lot of much time fine tuning the individual shots with Lightroom. Once I’m happy with how the middle exposure looks I’ll hit the Sync button to apply my settings to all three shots. Then you can combine the shots into a single HDR by right clicking one of the three images (in the filmstrip of Lightroom’s Develop module) and choose “Edit In > Merge to HDR Pro in Photoshop”.
Once you start the process you can probably take a break and grab a beverage because this might take a while. Depending on how big your image files are (especially with cameras over 30 mega-pixels), how many shots you’re merging and how powerful your computer is this process can take anywhere from a few minutes to almost an hour. Three 24 mega-pixel images take about 5 to 10 minutes to create a merged 32 bit per channel file with my MacBook Pro. When you come back to your computer you should see a screen that looks like this:
All I do at this point is click the remove ghosts check box and make sure my mode is set to 32 bit. Here’s a closeup of the HDR Pro dialog in the upper right of the screen with the remove ghosts check box and mode setting circled in red:
Now I click OK to open the image in Photoshop. Don’t worry if it looks terrible because that’s normal. You’re looking at a 32 bit image and that means that there’s a lot more information in the darkest and brightest areas of the image that you can’t see yet. I’ll talk more about 32 bit per channel files in Part 2 of this blog series.
To get the image to look good you still need to tone-map the file. Here’s what the 32 bit Phantom II file looked when it opened in Photoshop:
It looks really dark and not very good. At this point I save the file so that I can experiment with different tone-mapping techniques. I click “File>Save as…” to open the save dialog. To save the entire 32 bit image I save the file in the .tiff format because Lightroom 4 can tone-map a 32 bit .tiff file or you can open the .tiff file in Photoshop (or another program) and do your tone-mapping there. By saving the 32 bit .tiff you have a “master file” to work with in whatever program you choose.
With the file saved I’ll go ahead and tone-map the file in Photoshop HDR Pro by changing the files bit depth from 32 bit to 16 bit. To change the bit depth to 16 bit click “Image>Mode>16 Bit/channel…”. Here’s a screen capture of where this is located on my Mac:
Doing this will bring up the Photoshop HDR toning dialog. Here’s a screen capture of my Phantom image with the HDR Pro dialog open:
Now it’s looking like something. At this point you can do one of two things. You can start moving sliders until you get an image you like or you can choose a preset from the preset drop down menu. I’ve gone the slider route in the past but now I just grab the Scott5 preset (created by Photoshop instructor Scott Kelby) and I make some small adjustments. The Scott5 preset is a great starting point for tone-mapping shots like this. For this image I used the Scott5 preset then I increased the shadow slider to bring out some detail in the darker areas of the image.
One last thing, be sure to check the Smooth Edges check box (below the strength slider). Doing this really helps most images so check out your image with it checked and un-checked. I liked how it looked with the edge smoothing so I left the option checked. Next I click “OK” to let Photoshop apply my tone-mapping.
At this point it looks much better but it probably still looks a little blah (and that’s also normal). We’ve created a tone-mapped image but that doesn’t mean we’re done. You can choose to start working on your image in Photoshop (that’s what I usually do) or you can save the image as a .psd file and import it into Lightroom where you can process your image with all the great sliders there. I’ll stop here and just say that I kept the the tone-mapped image in Photoshop where I did some serious color work to get the color casts out of the jet fighter. Then I added some mid tone brightness, increased overall contrast and I added a glow to the image (with the glow eliminated from the F-4S with a layer mask). Here’s a look at the final image when I tone-mapped the 32 bit/channel file in Photoshop HDR Pro:
I like the image but it’s a little over the top and a bit moody. When I was at the Air & Space Museum it didn’t look anything like this image. The floors didn’t look this grungy, the F-4S certainly didn’t look anything like this and the room was considerably brighter. Sharing this image is cool if you’re going for this look but it isn’t very natural looking. If you show it to people that say they don’t like HDR images they probably won’t like it. And that’s totally fine. This is just one possibility. At this point I save the image (as a .jpg file). I can either share it like it is or I can bring this version back into Photoshop as a layer and combine it with a different version (like the non-HDR version we created at the beginning of this blog entry).
Although I said this version of the image looks “over the top” and moody it does have some qualities I like. I like how the roof in the background looks, for example, and if I create a more natural looking version I think I’d like to see how this roof would look blended into that tamer version.
With this version of the F-4S finished it’s a good point to take a break in this blog post. In my next blog entry I’ll share my Lightroom 4 tone-mapping technique and I’ll blend in the Photoshop HDR Pro version to get some added detail in my final image.
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