Learn the basics of HDR photography
A guest post written by Michael Mellon
HDR. Short and Sweet.
In this article I am going to teach you the basics of HDR photography. There are a few books out there that go in-depth on the subject, but for this article I’m keeping it just short enough where you can learn the basics in about 20 minutes. However, if you would like to purchase a great book on the subject I would highly recommend Practical HDR, found here.
Now, there are two different types of HDR photos in my opinion. There are the ones done right that really help enhance the photograph. And then there are ones that are too cheesy and overdone. I am sure you have all seen both sides of the spectrum. I’m not going to call out those that are good and those that are bad, because it is all subjective. I will say that there is a place for HDR, but it does not work in every situation. For one, you rarely see good HDR images with people in the frame. That is because true HDR is done with a bracket of exposures. Have you ever tried to shoot a bracket of 7 exposures with a person in the frame? It’s pretty hard to get them to stand still for that long.
For those of you who don’t know, HDR stands for High Dynamic Range. This phrase is key. Most modern digital cameras can capture about 5 stops worth of light. But how many times can you recall photographing a scene where there was considerably more than a 5-stop range from shadows to highlights? It happens all the time. Mostly outside when the sun is overhead, giving you that high noon, high contrast light. So what can you do in this situation to capture the entire range of the scene in one frame?
One solution is to take 1 exposure for detail in the highlights, and a second exposure for detail in the shadows. Take those two photos and merge them into one in Photoshop. I am sure you have all done this before. And hey, for what it’s worth, it does its job. Let’s not forget that you have to mask certain areas, and paint through one layer to reveal critical parts of the scene onto the top layer. It can be rather tedious. There has to be a better solution! This is where High Dynamic Range Imaging comes in.
The key to making a good HDR image is to cover yourself with multiple exposures. The best way to do this is to use your histogram!! Yes that weird graph looking thing that you probably never pay any attention to while shooting. Well…start using it! Not just for HDR photography, but for all of your photos. You need enough exposure in your shadows to ensure adequate detail, as well as enough exposure in your highlights to ensure they do not blow out. Another important note to remember is ALWAYS USE A TRIPOD. No matter how hard you try to keep things lined up, you will always move a little bit in between frames. Even though Photomatix has a feature to align frames, it doesn’t work. And that is just something you can take care of before the post-processing. Also, use a remote shutter release if you have one. If not, utilize the timer on your camera; anything to avoid camera shake. Let’s take a look at a bracket of exposures I shot to create an HDR image.
Now usually I will end up taking at least 5 exposures to ensure I have full detail in shadows and highlights. In some situations I will end up with 7 or even 9 exposures.
These histograms are not ideal. The middle photo should have more data in the middle of the graph. I am certain I metered off of the sky, rather than the buildings. That is why there is a pretty large gap in the middle of the graph and why most of the data is towards the shadow end of the graph.
As for the underexposed and overexposed images… If I had taken two additional exposures I would have had an even better result. As I said before, on the two extremes, you do not want your data to be touching the sides of the graph at all (ideally).
After the images are shot, you need to process them. The best program, in my opinion, is Photomatix Pro. It is really easy to use, and yields great results. There are one or two others out there, but I have not used them. I have heard both good and bad things about all of the HDR software. Yes Photoshop has a “merge to HDR” feature, and I encourage you to give it a try as well.
I could go really in-depth here and tell you what to do, how to do it right, and show you all of the controls that Photomatix has to offer, but that would end up becoming more of a novel than an article. This is a basic HDR tutorial.
Here are the basic steps for creating your HDR image in Photomatix.
1. Click “Create HDR Image”.
2. Browse for your complete bracket of images. USE RAW IMAGES. DO NOT CONVERT TO JPG. YOU WILL LOSE LOTS OF IMPORTANT DATA IN YOUR IMAGES.
3. Click “OK”.
4. Click “Align Source Images by correcting horizontal and vertical shifts”.
5. Click “Reduce Chromatic Aberrations”.
6. Click “Reduce Noise”.
7. Click “Attempt to Reduce Ghosting Artifacts” if you have moving objects that are moving in your bracket, such as birds, flags, cars, water, etc.
8. Choose your preferred White Balance.
9. Click “Generate HDR”.
Once the process is done you are shown a 32-bit HDR image. The reason it looks so awful is because monitors are not capable of displaying 32-bit images. You have to Tone Map the image. This refines the image even more, and turns it into a viewable, 16-bit image.
There are many controls that you can change to tweak the image to your liking. No two images should ever have the same presets.
Once you finished the image, click “Process”. Voila!!! You’re done.
Save the image and then open it in Photoshop to adjust the basic things you normally would. Enjoy the endless possibilities of HDR!
More samples of HDR Photography:
And as an extra bonus, the Awesome people over at PhotoMatix have given us a coupon code to use for anyone interested in their software. If you purchase PhotoMatix (can download at: http://www.hdrsoft.com/download.html) use the code “DigitalPhotoBuzz” (without the quotes) to give a 15% discount on the price of the software. The coupon has to be entered in the ‘Coupon code’ field of the order form that shows after having clicked on one of the “Buy” buttons of the purchase page of their website.
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