HDR stands for High Dynamic Range, which sounds geeky (and it is) and scary (which it isn't). In short, it is a technique that can create photos that match the ability of the human eye to see extremes of light and dark (i.e., the range part of high dynamic range) at the same time—an ability that cameras actually lack!
Why should real estate agents concern themselves with HDR? There's no doubt that people are visually-inclined. Assuming two listings are practically the same in price and features, the listing with the better photos is likely to get the first consideration. No one wants to see a home that looks like a dark dungeon. With the right tools (or photographer/artist), an HDR photo taken at dusk can make even your least expensive property look like a magical castle. I certainly can't afford a million-dollar home, but I'll often look at agents' listings that use HDR photos just to see how amazing the images can look. Our own office's Wyatt Poindexter uses HDR photos in many of his listings.
Underexposure vs. Overexposure
In the second image, the camera adjusted correctly to the sky—you can see all of the detail in the clouds, and the bright blue of the sky is actually blue, not all white! However, the house suffers for the brightness of the sky by becoming too dark.
This battle between light and dark areas of photos is exposure. HDR aims to "balance" the extremes by showing both correctly exposed areas in one, single image. Another way to think about what HDR means is "balanced brightness" or "merged exposures".
How HDR Photography Works
Once the two (or more) photos at different exposures are taken, the post-processing can begin. This usually means importing the images into a application such as Adobe Photoshop, and allowing the software to "merge" the areas of the images where the exposures are correct. The image below illustrates what I mean.
The final, HDR photo better approximates what the human eye can see. Certainly if we were to stand in front of a house on a bright day, we could see the clouds in all of their detail on a blue sky as well as all of the dark nooks and crannies of the house's exterior—something a camera cannot do without some help.
Realistic HDR vs. Surreal HDR
Below, you can see the differences in all of the images I've discussed: underexposed, overexposed, realistic HDR, and surreal HDR.
If you want to see (mostly) surreal HDR images, just do a Google image search for HDR.
How to Take HDR Photos (with an iPhone)
To take a good HDR photo, you will need...
- an iPhone 4, 4S, 5, or later (iPhones before these models do not have a true HDR feature built-in.)
- an iPhone tripod, or a very, very steady hand. (Here is a cheap (price and quality) iPhone tripod from Amazon.)
- a location with areas of high light/dark contrast (Taking pictures of architecture on bright days, or semi-dark indoor areas with small lights and lots of dark detail (a Christmas tree, for example) work well.)
Follow the screenshots below to enable HDR photo capture on an iPhone.
You may also wish to enable "Keep Normal Photo" under Settings > Photos & Camera. This will cause the iPhone to save two (2) photos to your camera roll. Instead of just one HDR photo, you will have one HDR photo and one non-HDR photo for comparison purposes, if the HDR photo came out blurry, or the non-HDR photo may just look better!
Have fun with HDR, and remember: Practice makes perfect!