Computersight -

What is an HDR image?

HDR stands for High Dynamic Range and allows you to merge several images together to create an incredible range of tones and detail, that simulates what the human eye sees.

They are especially useful in low light situations or areas where you have two subjects lit differently, such as a bright window or a night time scene, but they can enhance many photographs by allowing you to manipulate more information in the highlights, midtones and shadows.

Step 1: Taking the Picture

For my HDR image I decided to take a night time photo of some steps. I used a tripod so my image would remain consistent for all three shots. Because we are placing photos on top of each other, any movement would create a ghost effect where the images are different. If you have a remote shutter, you can use that to further help keep the camera steady, especially when using long exposures like in the case of this night time scene.

Keep the f-stop the same, changing only the shutter speed for each image. This process is known as bracketing and you’ll need to put your camera into manual mode to do it.

You may take as many exposures as you like, but I am keeping mine simple with just 3:

It was a windy night and my tripods not very sturdy, so the focus on these is going to be a little soft.

My first shot is underexposed, with at F13 for 2 seconds

My second shot is more accurately exposed at f13 for 4 seconds

My final shot is very bright, shot at f13 for 10 seconds

Now I’m ready to start merging my photos.

Step 2: Merging your photos using Photoshop’s HDR tool

For this process, you may want to use either Photoshop CS3 or Bridge, which comes with Photoshop.

To use Photoshop:

Go to > File > Automate > Merge to HDR…

At this point, a box will open that allows you to either select open files or browse for files on your computer. If you use select open files make sure you don’t have anything extra opened. If you are using RAW images I recommend browsing for files so you don’t have to covert these before you merge them.

Once you click OK Photoshop will begin open this window you.

Don’t worry if the image doesn’t look very good at this point.

Change the file to 16 bits/Channel and select OK. Photoshop will merge the images.

Select Local Adaptation and Click on the Arrow by Toning Curve and Histogram

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By adding points to this curve and adjusting it into a simple S curve, I can create contrast without losing too much information. Just play with the curves until you get an image that you looks the best. If you accidently create a point you don’t want, simply click it and hit delete.

At this point, my image looks something like this:

Now this image has a very smokey quality to it.

This can be helped by going into Image AdjustmentsHue/Saturation or by clicking Ctrl + U ( Command + U for you Mac users) and pushing the saturation up just slightly.

I also thought the midtones turned out a little washed, so I went into ImageAdjustments Levels and slid the middle slider to the right to darken those.

As a final step go to ImageMode 8 bits/Channel – Here is my image.

HDR image Middle Exposure

Looking back on these images, I should have taken more bright exposures, to get my full range of shadows.

Either way-I hope your HDR images come out looking great!

Feel free to send me some examples of your own (and hopefully better looking) HDR images.