Many people that are selling a home call and say "I want HDR photos" but when I ask them to elaborate on what they mean, they're not really sure. The problem stems from the fact that "HDR" has such a vague meaning and is often something only experienced photographers understand.
HDR is an abbreviation for High Dynamic Range. In the simplest terms, this means that the photographic image has a wide tonal range, with detail showing in both the bright and dark areas of the image (the highlights and shadows). This wide tonal range is often not something that can be achieved by a simple push of the button on the camera and instead requires some sort of post-processing (Photoshop). Different photographers will approach this task differently.
Some photographers will use techniques that result in images that have hyper-saturated colors and extreme detail, that look almost cartoon-like. Other photographers will use techniques that produce images that look more natural, while also showing a wider tonal range, such as a brightly lit interior and at the same time, showing the beautiful view through the window. For most people, I think the latter is what they're really asking for when they ask about HDR, particularly with real estate images. So, if what you really want is the view through the window to show clearly, it's best to state that, rather than asking for HDR. Because with HDR, you never know what you're going to get.
(If you really want to have a basic understanding of what this all means)
Unlike our eyes, cameras are not capable of capturing the range of tones in scenes that go from very, very bright to very, very dark. For instance, say an image is taken outside on a bright sunny day. The brightness range can be extreme, from the white paint on a house (highlights) to the shaded area under a porch roof (shadows). This range may be 30 incremental steps from light tones to dark tones. A normal camera is only capable of capturing 10-14 consecutive steps of this range, so the photographer has to choose – should it be the steps at the light end of the scale, or the dark end? Or somewhere in between? If the photographer chooses to capture the steps near the bright end of the scale, then he sacrifices most, if not all, of the detail in the darker areas of the image. Those areas may just go to black. It's just the reverse if he chooses to capture the tones at the dark end of the scale.
To solve this problem and get images that have detail in the brighter areas as well as the darker areas, the photographer will capture a series of images of the same scene. Some images will show the brighter detail, some will show the detail in the mid-range, and some will show the detail in the very dark areas. These images are then taken into Photoshop or some other graphics program and blended together, using the bright areas of one shot and the dark areas another shot, to produce a final image that has a higher range of tones than would an image taken straight out of the camera. Technically speaking, this resulting image is a “high dynamic range” photograph.
Again, every photographer will approach this differently. Some will simply use the "merge these images" option and live with whatever the results might be. Oftentimes, the resulting image is murky, with over saturated colors that can look a little surreal. Other photographers will take a much more critical approach and carefully hand blend each area of the image, ending up with crisp, realistic looking images. Personally, I prefer the latter.
Each of these approaches can be considered “HDR”. But the techniques and results may quite different. That’s why asking for “HDR images” may leave the photographer guessing about what you’re really after.