Before we learn how to make an HDR photo, we need to learn exactly what an HDR image is.

An HDR image is one that has a increased, or “high” dynamic range. What is dynamic range? Well, it’s basically the range of exposures that can be properly displayed within a picture. Think of it this way: when you’re standing in a dark room, with a door that leads into a bright hall, you can easily see the details in the room, and in the hall. Unfortunately, a camera cannot do this, normally. A camera will either be set to expose the brightness of the hall, and have the room be dark, or have the room exposed properly, but then the hall will be blown out. It’s almost impossible to fix this with a single exposure.

How we fix this, you say? Well, if you guessed we make an HDR picture, you’re exactly right. A HDR image is a photograph which is composed from several shots of the same scene, all taken at different exposures. By using a tone-mapping program you can easily merge the differently exposed shots into one, “high range” image. Here’s how you do it.

Choosing a Scene

The first step is to find a scene with a large exposure range, like something including both a bright blue sky, and a dark shadow. The higher the range, the more striking the final result. Try experimenting with different types of scenes. Remember, a scene that may not look great in the viewfinder can look amazing after it’s been tone mapped.

Shooting the scene

You’re probably wondering how many shots you should be taking. There is no set answer to this. Instead, take a educated guess, based on the exposure range. If the sun and a shadow are in the same picture, then you’re going to want to take 5 or more shots. I usually go with 3 images, each one set 2 exposure stops apart (-2, 0, 2).

Remember, the more shots you take, the clearer and cleaner the final image will come out. It’s better to take 5 shots (-2, -1, 0, 1, 2) then taking 3 shots (-2,0,2), because more detail will be added to the final image. Although, this also lengthens the amount of time it takes to create the HDR image, so the choice is yours.

For my example, I picked a scene from my backyard. It’s got a good contrast range, and also some good colors. Unfortunately, because there is such an exposure range, most of the colors are blown out.

Here’s the three exposures I took. Note how you can see either the darkest or the brightest parts of the scene if you take bits from each frame.

Creating the Tone Mapped Image

Now that you have your three images, we need to create the tone-mapped HDR image. There are a few programs that can do this, but I prefer Photomatix, which you can grab here. It costs $99, but is well worth it.

First, open up Photomatix, and then click on the “Generate HDR” button. Then select Browse, and select your three images. I used three RAW files from my D40.

After you’ve selected your images, click OK. Photomatix will churn away and generate a 32 bit HDR image. Think we’re done? Nope. Not even close. The truth is, your monitor cannot display 32 bit images properly, so we need to do some tone-mapping. Click on the “Tone Mapping” button and you’ll be taken to a new window, with new controls.

As you can see, without tone mapping, the image looks nothing like a polished HDR.

Basically, what tone mapping does, it is take the huge 32 bit range of the image, and compresses it down to something your monitor can display properly. Usually 16 or 8 bits.

Here’s a quick rundown of what all the different buttons and levers do in the Tone Mapping dialog. Don’t worry if it looks a bit complex at first, you’ll figure it out in a jiffy.

Strength

The overall HDR style. If you want that vibrant and contrasting HDR style, slide Strength to the right. If you want more typical, lower contrast colors, slide it to the left

Color Saturation

The Saturation of your image. This functions like the saturation slider in Photoshop.

Light Smoothing

The “blending” between the different brightness levels in the image. Set it lower for a image with more punch, but looks very surreal. Set it higher for a better blended image, but has more real-looking light

Luminosity

This slider is sort of hard to explain. It effects the “halos”, or brightness around the images. Set it to the right to remove these halos, set to the left for more halos.

White Point

Effects the intensity and level of white in the image. Set it to the right to increase the brightness of the bright part(s) of the image.

Black Point

Effects the intensity of the black level in the image. Set it to the right to increase black level. If you want an intense-looking image, slide both the white and black sliders all the way to the right.

Gamma

The overall brightness of the image.

Once you’re done playing with the different buttons, knobs and levers, hit Process. Photomatix will churn some more, and spit out your fully tone-mapped image. You can save it in the FIle -> Save As.

Now, if you’re happy with the image right now, then you can stop reading. You’re done! But, if you want to add a bit of spit n’ polish to your HDR, keep reading.

Step 2 - The Photoshop Effect

While Photoshop’s HDR processing may not be wonderful, you can certainly harness the power of Photoshop to add some shine to your HDR

If there are small bits of your HDR that look noisy, or just plain odd, we can fix ‘em easily here.

Take your HDR, grab the eraser tool. Now, start erasing the problem areas. Don’t worry, we’ll fix them in a second!

Now, you need to do a bit of thinking. Look at your three original shots. Which one best matches the exposure around the area you erased?

Open up that shot, and add it to the HDR image, one layer below the erased shot. Make sure it’s lined up properly, or you’ll end up with a really weird looking image.

As well, you can play with the Contrast, brightness, hue, and more to get just the image you want. Here’s my final image.

Another Option - Creating an HDR from one RAW File

Now, what if you want to make a HDR, but you only have one RAW image? Say if you shot a picture during a sporting event, or while you were moving. Photomatix can do this too, but your results won’t be as good as using 3, 5, or more images. There’s less data going in, so there is less data to create the HDR image.

To do this, fire up Photomatix again, but this time, open up Finder too. Simply drag your RAW file onto the Photomatix icon.

You can also do this from the menu option Automate -> Single File Conversion, this offers a far more complex dialog box, that you probably won’t need. I find dragging a file onto an icon is much faster.

Creating & tuning the HDR image created from a single file utilizes the same steps as a multiple file HDR, so simply follow the steps shown above.

As you can see, the image created from a single File is OK, but it isn’t wonderful. Try to take 3+ shots at a time, if you can.

Remember, the key to creating cool HDRs is to keep trying. The more HDRs you create, the more experience you get. Have fun, and don’t take it too seriously!