Shooting the Impossible

HDR

By Peter Tellone Back to

Peter Tellone, hdr photography, high dynamic range, photo technique HDR example using Photomatix Pro 4.1, even though we have two very bright objects in the image (The sun and the white water) we still retain detail in the shadowed rock area.

I love my cameras because of the possibilities that they hold, but sometimes I feel cheated by them. They always have, first with film and then digital, captured what the film or the digital sensor was capable of “seeing” but not what my eyes saw and I have always known there is a difference.

Because of that difference there were beautiful things that I could not capture because of the limited dynamic range that film or digital sensors had compared to my eyes. One of these impossible things was including the sun in the frame and not intending to have a silhouette shot.

About five years ago, I found out about High Dynamic Range Imagery (HDRI or HDR) and quickly became intrigued about the possibility to shoot the impossible and capture what my eyes could see. I’ll share with you how I make my HDR images by combining several into one. This will get you started and allow you to experiment and get used to the process of shooting for HDR and how to bring it all together in your computer.

Peter Tellone, hdr photography, high dynamic range
Another “Impossible” image. There would have been no way to retain the detail on the shadowed area of the arches and not blow out the sky and sun portion of this image using conventional methods. And this was as the eye saw it.

Equipment Needed
· Camera that is capable of manual operation or exposure bracketing in Aperture Priority mode
· Steady good quality tripod
· Remote shutter release for best sharpness (although it is possible to use your timer or just press the shutter button)
· HDR Processing program. I use Photomatix Pro 4.1 from HDRsoft. There are many more and you can even use Photoshop CS2 or later to process HDRs.

Image Capture
You’ll want to capture the highest dynamic range for each image even if shooting multiple exposures. If your camera is capable of shooting RAW or Tiff format, do so. You can shoot JPEGs, it will still work fine even if it is not the ultimate in quality. Determine a good subject and lighting for HDR. Landscapes are a natural for it and are best shot early morning or late in the day when light gets more contrasty or has more dynamic range. Architecture is good, interior architecture and vehicles may also work.

Look for a subject that you can’t capture well with normal photography. To determine if you have a scene with enough dynamic range to try, do this test. But first a caveat; if the sun itself is in the frame, you have more than enough dy- namic range. And never meter, or look directly into the sun.

1. Set your camera to manual and spot or center metering.
2. Meter the brightest part of your scene. 3. Adjust your exposure so that it reads +2 on 4. Now move to the darkest portion of your scene.
5. If the meter now reads -2 or more, you have enough dynamic range.
People or anything in motion are not good for HDR because you need multiple exposures−any movement in-between those images will cause ghosting in the final image.

Peter Tellone, hdr photography, high dynamic rangeFor this basic tutorial shoot three images at three different exposures. Use either manual mode or aperture priority auto. Be sure and choose aperture priority over shutter priority because you want the aperture and therefore the depth of field (DOF) constant. I always shoot my HDRs with a smaller aperture.

I usually use f/16 on my full frame camera that gives me the maximum DOF without getting some softness issues that occur at even smaller apertures. If you are shooting with a cropped DSLR you should probably shoot around f/11. Use the same aperture for every shot.

With the aperture set take three shots. You need to have each shot 2EV or two stops apart. So if in manual mode, that would mean one shot each at 0, -2 and +2 on the meter. If you are using aperture priority mode on your camera that can do ex- posure bracketing, you want to set bracketing at three exposures, two stops apart.

If you did things right you should have three images that look similar to this:

Download your images to your computer and open them to view in appropriate software. You want a browser where you can see your images and define the file numbers for your set of three images. (Photomatix does have a Lightroom plug- in that allows you to take your images directly from Lightroom).

Click on the Generate HDR imagebutton and it will open another dialog box that you can browse for and find the images you want to combine into your HDR.

Peter Tellone, hdr photography, high dynamic rangeAfter you have selected your image and clicked OK your next dialog box should look like this:

Align source images will be checked, I normally check by matching features.

You will also notice a Don’t crop box. When Photomatix aligns the images, if they are off in alignment it will crop the image to remove the bad edges. Sometimes this leads to an image slightly ‘off’ from the regular 2:3 photo image. You may need to crop later to bring it back to a standard aspect ratio.

Reduce chromatic aberrations: I usually check this, it stops the blue/purple fringing that is common place on areas of extreme contrast.

Reduce noise: I rarely use. There are better noise reduction programs out there that I will use later if necessary.

Remove ghosts:I will use this if there are objects in the image that may be a problem, people or water moving. But if it is not necessary I keep it off. Most times I do leave it off. However the with Selective Deghosting tool of Photomatix is one thing that takes it a notch above other software.

The last two boxes are for white balance and color space. Choose the color space you edit in. If you DON’T know what that is choose sRGB. And white balance I leave as shot. If there are really problems with white balance I corrected them in my RAW editing program and then save the file as a Tiff to open in Photomatix instead of a RAW file. It is much more precise.

Peter Tellone, hdr photography, high dynamic rangeWhen ready, click OK and Photomatix will process the three images into a single 32bit HDR image. It will look somewhat like this, pretty ugly isn’t it?

In fact the worse it looks at this point, the better your HDR image will most likely look. That is because no monitor or printer available now can display a 32 Bit HDR image. So now you have to take this image and Tone Map it so that it is visible on the monitor and be ready to print.

Also at this point you can go to File> Save and save this as a Radiance RGB HDR file. This will allow you to reopen the original HDR file and rework it if you don’t like what your first attempt at tone mapping did. It eliminates having to do the first three steps again.

Click on Tone Mapping and the next and final dialog box will come up.

At the top are two buttons, one for Tone Mapping, one for Exposure Fusion. We’ll use tone mapping for this tutorial. Next is a dropdown and you can choose Detail Enhancer or Tone Compressor. The tone compressor is fine if you want a very natural looking image but really isn’t that powerful. I prefer detail enhancer not because I want something that looks unnatural but just that is gives me much more control and the ability to fix problems that may pop up in an image.

Peter Tellone, hdr photography, high dynamic rangeThis panel is set up with the most important settings at top and they work their way down in order of importance or use.

The two most powerful controls as you work down the panel are Strength and Lighting Adjustments. In the lighting adjustments panel check the box for Lighting Effects. This again will give you more powerful choices.

Between Lighting Adjustments and Strength, these two controls will adjust the differences between brightness and shadow and the intensity of those areas. Go back and forth with both of them until you get the desired look you want, without ugly artifacts that can be a side-effect of too much or too little of each other.

I usually start with Naturaland then move the strength bar back and forth till I find what I want. But depending on the image and what I am looking for I may go up to Natural + or down to Medium, again adjusting the strength to get where I want to be.

Luminosity raises or lowers the global brightness of the image. Once you get the ratio you want of bright-to-dark this will bring it all up or down.

Micro-contrast can bring in more detail to the image by increasing contrast at edges.

I usually raise Saturation a bit because with the blend of three images at extremes can make the image look a little flat.

Peter Tellone, hdr photography, high dynamic range
A screen shot of Photomatix Pro 4.1 during the tone mapping process, showing the image preview and windows for the Adjustments palette, Presets palette and Histogram.

Moving down to the next section, these are your tone controls. White point affects bright tones, Black point affects dark tones and Gamma affects mid-tones. Gamma is the control in this section I use the most. Since again, when you blend the three images it tends to make the whole image more towards mid-tones. You’ll need to bring some contrast back to it.

The rest of the controls are for precision tuning areas of the image, like shadow or highlight areas. They are very helpful when you run into problems with an image such as ghosting or haloing.

For my sample image, I set Strength at 70, Smoothing at high, Saturation at 70 and then Gamma at -1.20 and that was about all I had to do and this is my result for a look as I saw the scene when I shot it.

If this is the look you want, go to File > Save and save the image. I prefer to save it as a 16 bit Tiff file and then I will add some finishing touches in Photoshop. But you also have to option to save as an 8 bit JPEG file.

Just remember; in the end, we are actually making a Standard Dynamic Range image by compressing a very wide dynamic range image, because that is all that is possible to currently display. But you do want it to fully cover that range and simulate as best we can what our eyes can…see.

Resources: Software: Photomatix Pro 4.1, hdrsoft.com.

Peter Tellone, hdr photography, high dynamic range
Oceanside Pier Perfect Sunset

About the Author

Peter Tellone
PTellone
Peter Tellone is a Freelance Photographer, Author/Writer, Teacher and Mentor in Southern California. He specializes in Fine Art Landscapes, Concert and Street Images. His current lecture,... See–A Photographer’s Vision talks about how an artist sees and the special ways that artists need to learn photography. petertellone.com.