The old curmudgeon asks, what is all this HDR crap?
He has a number of answers.
1. HDR (High Dynamic Range) is a series of techniques to assist digital photographers to match the dynamic range of the human eye (depends on who you ask, but that's between 9 and 11 f-stops -- a lot, in simple terms). Digital cameras typically have a range of 6 to 7 stops, max.
2. HDR is used to rescue photos which suffer from camera (or most likely operator) limitations. If the scene is flat as a pancake, lacking highlights or shadows, HDR can help you create them where they were not.
3. HDR is yet another means for the talentless to ape the truly creative people who understand light, contrast, and color.
4. HDR provides endless proofs of HL Mencken's jibe that "no one ever lost money underestimating the taste of the American public."
The old curmudgeon may be tactless, but he's not stupid. Still, his less than temperate remarks merit a little elaboration, lest the unwary simply dismiss him with a shrug.
HDR is in fact a procedure to create a dynamically rich image where the original RAW interpreter saw a very limited image. In short, it's a method of making a silk purse out of nature's occasional sow's ear.
Today there are a ton of gimmick-laden HDR applications. You don’t need them to achieve a good result –especially if you shoot in RAW. If you shoot in JPG mode, you're cooked, so fuggedaboudit. (You may THINK you're OK, but then look at your image at 100% size, that is, 1 image pixel = 1 screen pixel, and you'll soon see how bad things look). All you really need is one more or less correct raw exposure. Make three copies of this exposure, set the exposure control to -1, 0, and +1 stops (or more, depending on what you want to accomplish). Open all three images in photoshop, copy them as layers to a master image, then erase as needed to get the enriched image you wanted.
This is oversimplified, but not by much. What this basic technique allows you to do is to put details into shadows and bright areas where there were none before, as well as make the darks darker and the brights brighter.
You get better results if you take multiple bracketed exposures of the same scene, knowing you’ll be using HDR techniques back home. If you use three or more registered images (registered means they overlap exactly, which means you use a GOOD tripod. use mirror pre-up, and use time delay so your heavy footsteps and clumsy hands don't cause vibration), you can stack these up the same way as you stacked the light-normal-dark version of just one image in the last example. You'll get even better results than using a single image. No gee-whiz app needed.
Doing it yourself is the hard way. Gee, it requires forethought, judgment, patience, and an understanding of what current light conditions and your camera can accomplish. God help you, you actually have to know something about photography to make the most of this technique. Arrrrgggghhh! Why go to the trouble when you could let the software do it automatically?
If you take the trouble to do things manually, you can get a rich image that really does go beyond the interpretive software's limitations (RAW images, remember, are 1-0 and that's it. You cannot open and view a RAW image -- someone's software must do the interpreting of what the 1-0 stuff represents visually). What you DON'T get is super-saturated colors, ethereal glows (Photoshop's built-in HDR routine actually has a setting for "surreal"), or butt-ugly, unconsidered color and lighting shifts.
OK, let's assume you are a rank and tasteless amateur who thinks HDR is the greatest thing since cranberry juice and kahlua cocktails. If you're one of that class, you are enamored of the super-duper effects HDR apps can create. And if you're really good, you can produce images that look like 1960s-era sci-fi magazine covers -- over-colored, air-brushy, with very hard edges. Yowzah! Of course if you're not that good, and keep tweaking the controls, you get things that look like a radioactive turtle emerging from a neon-colored mudbank -- only it's a picture of your infant niece, or, worse, your pregnant niece! Double araaarrrrrgjh!
This is a vital point. To use HDR, or any image-manipulation tool, effectively, you HAVE TO KNOW WHAT YOU WANT TO ACHIEVE. I don't mean you have to put it in words -- but you have to have a vision of what will be the right treatment for THIS image, what will best express the vision and feelings you had in your mind when you took it in the first place.
I'm not trying to discourage folks from trying HDR. By all means, tinker to your heart's content, learn the plusses and minuses, the ins-and-outs of this technology. But please, please, DO NOT thrust your baby steps on an unwilling audience, and then expect praise. At the very least, have an idea in your noggin of what you want to achieve, and how you want people to respond to it BEFORE you play with the buttons, and ABSOLUTELY before you post an over-colored dish of M&Ms and try to persuade us it's an orange souffle.
HDR apps invite the most wretched excesses and encourage people to rely on technology when their inner eye has no clue as to what they want to achieve. But -- and this is important -- the problem is not in the apps. Yes, they invite pictures that make the old curmudgeon run for a barf-bag. But they don't have to be used that way. Like guns, or helicopters, or motorcycles, they can be used for good or ill. Like any tool, they depend on the judgment and skill of the user to be effective. To be blunt, James Cameron achieved HDR / CGI miracles in Avatar, but very few of us are James Camerons!
Properly used, HDR can salvage deficient photos, enrich good ones, or bring a spot of magic to an otherwise humdrum shot. But improperly used, HDR is yet another reason why modern photography is so often held in contempt – and so little purchased.
The old curmudgeon says, "take good photographs first, based on your eyes and your heart and your skills. Feel free to see what technology can do for you. But DO NOT thrust your infant failures and bad taste on the rest of us as if you have accomplished something great. You haven’t, and if you just rely on automated HDR programs you never will." Amen.