HDR…You Make My Dreams Come True
What if I told you there was a magical, mystical photographic technique that can make the impossible possible? What if there was a way to take a picture of a sunset and actually have it turn out just the way you saw it? What is there was a simple process to make works of art well beyond your artistic capabilities? My friends that wonder is already here among us and it’s name is HDR. So what do those three little letters mean? HDR or High Dynamic Range photography in its essence is taking multiple photos of a scene at different exposures and then taking the best parts from each shot. This is necessary at times because your eyes work so much better than your camera. You can look at a sunset and appreciate the rich colors of the lit sky against a darker background and surroundings. Our eyes are adaptive and can adapt quickly to a greater range of light than can a camera. Your camera just can’t compete, but HDR photography evens the playing field when the scene is unfair. All you need is a camera where you can control the aperture and shutter speed.
So when is a good situation to employ HDR? If you’re taking a photo of your friend outside in great light or you’re just inside taking a simple snapshot you probably won’t need to use HDR. Where it shines through is when there is a dramatic difference between the brightest and darkest objects in your scene. This happens quite a bit when you’re taking a photo outside during the day. The sky is much brighter to your camera than you think and many times if want to take a photo with the sky and foreground in the same shot you have to make a choice. You can choose to expose the sky properly. However this will cause everything else to turn out really dark or you can expose for the ground and have the sky blow out and turn white. This happens a lot with sunsets and makes taking photos of them difficult at times. It’s frustrating to have an immensely beautiful scene transpire right before your eyes, take a photo and then get back home only to discover the photo is nowhere near as amazing as you remember. HDR can help you record that scene as you saw it and not just as your camera saw it. Another time HDR is helpful is when you’re not supposed to be taking photos. In the middle of the day the light is harsh and bright causing shadows that are dark and highlights that are extremely bright. The dynamic range of the light is so wide there is no possible way to get a decent photo with your limited camera. You’ll lose either detail in the shadows, the bright sky or even both. HDR empowers you to shoot in situations where it’s near impossible.
Now that you’ve seen what a miracle process HDR is just how do you use it? HDR usually requires some forethought to what kind of light you’re going to have when you shoot, a few extra pieces of photo equipment and some software. The first step is that I like to plan ahead and know if the light I’m going to be shooting in is harsh. If I can’t help shooting in the middle of the day I usually plan on having to do HDR. I recently went to Arches National Park and knew I would be there in the middle of the day when the sun was at its worst. Knowing that ahead of time I came well prepared. That way I made sure to bring the gear I needed. The one piece of gear that you absolutely need is a tripod. If you don’t have a tripod then invest in one that’s sturdy and solid. I’m all for cheap, but an unreliable, wobbly tripod will do you no good. Another helpful piece of equipment, but not necessary is a remote cable shutter release. This will help you avoid camera shake while your camera is on the tripod giving you better results. You can get by without it, but it’s an inexpensive item that can really improve your results. Once you’ve taken the photos you need to get an HDR image you need a software program to process the images. Photomatix has been the preferred program of most photographers for years, but the latest version of Photoshop, CS5, now has HDR capabilities that rival any other programs. You can download free trials of each program and give them a try to see which one works best for you and just what kind of results HDR can give you.
With the proper gear in tow and an HDR program waiting for you at home you’re ready to make the magic happen. The basic idea of HDR photography is that you take multiple exposures of the same scene, each with a different exposure level. In essence you take a darker photo, a normal photo, and a bright photo all of the same exact scene. Luckily your DSLR has a mode that does all the work for you called exposure bracketing (check your camera manual to find out how to set it). You can set the bracketing anywhere from +/- 1/3 stop all the way up to +/- 2 stops of exposure. To get the best results and capture the greatest amount of data you want to set the bracketing all the way to the max. The exposure bracketing will allow you to take 3 consecutive photos each one with a different setting. It will keep the aperture setting the same for each shot so depth of field is unchanged, but will instead change the shutter speed for each exposure. I prefer to actually just shoot in Aperture Priority mode when doing HDR. Don’t be worried if the 3 photos you take look horrible because this is about capturing the greatest amount of data and not about getting photos with great light. You have to press down the shutter button each time to take the different exposures. A tip to make it easier is to put the camera on burst mode so that you just have to press and hold the shutter button down once while the camera rattles off the 3 shots for the bracketing. A remote cable shutter release makes this part easier. If you’re holding down the shutter button with your finger for the time it takes to do the 3 exposures you’ll probably cause some camera shake. Your tripod is the key to this whole process. The HDR process involves doing the exposure bracketing of the scene and placing the 3 images on top of each other. If the program places the images on top of each other and they don’t line up exactly you’re not going to have a sharp image. The HDR software tries it’s best to align the images, but without 3 images that are almost exactly the same you won’t get the best results, thus the grand importance of a tripod. Honestly it’s not worth doing HDR photos without a tripod (you can however improvise one if you’re in a pinch by placing your camera on a solid surface).
Once you’ve got the multiple exposures of the same scene taken it’s time to convert them from 3 horrible looking pics into something magical. Thankfully this is actually the easy part of the process. I’ll run through the process here using Photomatix. Open up the program and go up to the top menu. Click on Process->Generate HDR. In the window that pops up click on ‘Browse’ and find the 3 multiple exposures that you took. Select all 3 and click on ‘Open’ and then on ‘OK’. This will bring up the options menu. Most of the important options should already be selected for you. If your scene had trees, water, people or anything else that might have moved during the time you took the exposures make sure to click on the ‘Attempt to reduce ghosting artifacts’ box. This option helps to reduce blurry trees and people in your final image. It’s not perfect and you might have to do some clean up work, but it helps. Once you click ‘OK’ Photomatix will convert the multiple exposures into a single HDR image. This takes about a minute so be a little patient with it 🙂 Now don’t worry once it finishes. The image that Photomatix spits out looks even worse than what you could have ever imagined. I don’t want to get into the nitty gritty details, but suffice it to say your monitor can’t actually reproduce a true HDR image. All you can see is a horribly exposed picture with extreme shadows and highlights. In order to create a high quality image your monitor can display click on Process->Tone Mapping. Suddenly your hard work pays off and the horrible images you started with are transformed into a wondrous blend of perfect exposures. All the best parts of the multiple exposures you took are pieced together giving you detail from the bright sky to the dark shadows.
This will bring up the tone mapping settings window. There are a bunch of sliders that control the magic output. I’ll try to go over the important ones and what they do. It’s hard to explain such a visual process in words. The honest truth is if you want to learn what they do play around with the sliders. Slide it from one end to the other and see exactly how it affects the image. You won’t hurt anything.
- Strength – This controls the contrast of the HDR effect and in general the overall ‘HDRness’ of the photo. I personally like a higher number here. It gives the image a more painted quality and I like going a little over the top. In the end it’s a personal preference though on what you think looks nice.
- Color Saturation – Pretty self explanatory on this one. HDR images are known for their rich and wide array of colors. Be careful however not to get too carried away with the saturation. If you do too much the colors will start to bleed and you can have too much of a good thing here.
- Luminosity – Simply another word for brightness. Pretty self explanatory setting.
- Microcontrast – This is just a basic contrast setting.
- Smoothing – This setting is a little hard to explain in words. Try it out and see for yourself what it does. You probably want to keep it on the higher end. I personally only ever use ‘Max’ or ‘High’ because the lower you go the more psychedelic the image becomes.
- White and Black Point – I really don’t use these too often. I prefer to just do a level adjustment in Photoshop because the Photomatix sliders use numbers for settings that don’t really match up with the histogram.
- Temperature – Make sure this is set where you want it. Once you save the HDR image the temperature gets baked in and you’ll have to redo the post processing all over again to correct it.
- Microsmoothing – This is like a mini contrast setting. It smooths out the transition between colors and the different objects in the image.
- Highlight/Shadow Smoothness – These are helpful for adjusting the highlight or shadow exposures individually in the image. These are great for getting the final exposure levels just right.
Once you have things just the way you like click on ‘Process’ and you’re good to go. I like to then save the HDR image and open it in Photoshop for some touching up. I’ll do a levels adjustment, sharpening and some noise reduction usually.
As much as I’ve talked up HDR there still are however some limitations and minor flaws. One problem you have to worry about is noise. The photos can some out pretty grainy using Photomatix so running it through noise reduction software can help. Keep an eye on the noise when you’re adjusting your settings so and try to avoid extreme settings that really make the noise noticeable. Another limitation is you need a relatively still subject and background. There’s just not really any way to take an HDR of a race car or your kid playing sports. The software can handle fairly well small tiny movements, but if the wind is really kicking around the limbs on the trees you’re going to get a very blurry final image. I’ve also had trouble with it when taken an image at night. The software tries to expose the blackened sky and it turns into a horrible mess.
Clicking on the tone mapping button is pretty nerve racking because you don’t quite know what it’s going to spit out. There have been times when I thought this is going to turn out great and the resulting image that pops up looks like trash. But on the flip side there have been a few times where I haven’t had too much hope and have been wonderfully surprised by what the tone mapping process could do. It honestly takes practice to know when the situation calls for taking multiple exposures for an HDR image and when it won’t be so great. Luckily though more times than not you’ll come out with a winner. I still learn something new every time I try the process and have found though that when in doubt go ahead and do the exposure bracketing. If one of those shots turns out great by itself then that’s one less step for you to do and if not you can run all 3 through HDR software. Shooting with HDR in mind is a great safety net when you’re in tricky lighting situations.
There is still so much more I want to say about HDR, but I’ll leave that for another post. It’s pretty controversial actually in the photography community and there are definitely those who sing HDR’s praises like I do and some unfortunate souls who look down on HDR. I’ll save all that for another discussion 🙂 If you have any interest in photography give this process a try. It honestly is pretty much foolproof and so addicting. With such little effort you can achieve stunning results right out of the gate. Some of my personal favorite HDR’s are from the very first time I tried it out. HDR is such fun and so incredibly useful. I just love the rich colors and vibrant textures. It’s a technique that every photographer should have in their repertoire. So get out there and try it!