What is HDR or High Dynamic Range imaging?
Essentially, it is way to allow a greater range of tonal values between the lightest and darkest areas of an image. This is accomplished by taking multiple exposures, 1 normal exposure, 1 underexposed and 1 over exposed and then layering these 3 photos on top of one another and then doing something called Tone Mapping. Tone Mapping adjusts the overall contrast to bring out the the details in the light and dark areas.
The most popular and sophisticated HDR program is probably Photomatix by HDRsoft which is what I am using.
Now, I've seen a lot of HDR images and I have to say that they fall into three distinct categories: the good; the bad; and the downright awful. The good are the images that you didn't know were HDR, or the images that are clearly HDR, but are extremely smooth and free of artifacts and noise. They also have a strong composition that draws you into the photo. The bad are the images that could have been good if perhaps a little more time was spent on the processing (i.e. cleaning up the halos). And, the downright awful are the images where there was no thought to composition, excessive halos, noise and artifacts and just look like puke! You look at it and know that it's an HDR hatchet job. It doesn't matter how you slice it, HDR will not make a bad photo look good!
This was my weekend to try out HDR for the first time so I went out and took some test shots that I will explain below. After playing with HDR for a little bit, I can see why some may get addicted. It creates a really cool effect that is simple to produce. Trying to do something similar with Photoshop, unless you are guru or close to it, would take some time to learn and probably has more moves than Kung Fu. As with any new technique you may think "hey, this easy and it looks cool, I should do this for all of my photos!" I'll be honest, that went through my head, too, but then I thought about the good, the bad, and downright awful and decided that I would try create some guidelines for myself with hopes of staying out of the downright awful category at the very least.
- Restraint - I think this is crucial for all types of post processing. We have all seen photos that have been overcooked in one way or another and HDR is no different. Exercise some restraint here and try to keep things from looking overcooked. I think it's great to push the sliders all the way to the right to see what it looks like, but then back things off until they look more pleasing.
- Does it really need the be HDR? - I think this is a great question. HDR works best when you have a range of tones that is outside of your camera's ability to capture (usually about 5 stops is all a DSLR can capture). I realized after I got home that my test shots below were probably not the best to maximize the HDR effect. My normal exposures were pretty bang on, no clipped highlights or shadows which means that my D300 captured all of the tonal range for the scene. Did I lose any detail? Not really! So I was thinking, if my normal exposure does have clipped highlights (blinkies if you have your highlight warning turned on) then it may be a good candidate for HDR. Exposing for the highlights will loose detail in the shadows so create another exposure for the shadows and combine in HDR.
- Composition - Remember HDR is only a post processing technique no different than post processing in Photoshop. Also remember that no amount of post processing can save a really bad photo. This is the mantra of "get it right in the camera the first time". You still need to have a good composition and proper technique.
- Use a tripod - although Photomatix will auto align your photos, the tripod will minimize any drastic differences;
- Shoot in aperture mode so you can maintain the same depth of field throughout each exposure;
- Use auto exposure bracketing to set your exposures;
- Use continuous high speed mode if your shutter speeds are high;
- If shutter speeds are low (i.e. night shoot or indoor low light), you may want to invest in a remote/cable release to avoid camera shake.
This first one, to me, is slightly overdone and probably didn't really need to be done in HDR to begin with. My original exposure was pretty good with only a little clipping in the shadows as you can see in the original. However, it did bring out the colours pretty well. I like the composition, but I should have given more thought to the orange cones. I could have gone out on the ice and moved them or spent some more time in Photoshop to remove them. A second look and that black strip in the lower centre is a little distracting, too. But again, this was for testing only.
Second, there is still a little bit if halo fringing along the horizon. Did this really require HDR? Look at the histogram, it's a pretty well exposed original. Composition was not so strong so I adjusted it for the next image.
Third, pretty much the same scene, I just moved closer and put the horizon more in the upper third. Original exposure was not too bad either. I did get a nice "painted" effect, but there is still some glow along the horizon.
I do like the HDR effect and will try some more of this over the next little while. I'll also try to keep my my guidelines in mind for the next time, too.
Please feel free to comment or add some additional advice.