High dynamic range (HDR) photography has been around through film and digital technologies and whether you are attracted or repelled by the outcome of its application, it’s definitely here to stay. Some newer digital cameras are even starting to have HDR built right in to let you see what multiple images will look like before you download the images to your computer.
But this is not news to you, right? All you experienced photographers who are shooting multiple images across a range of exposures in order to keep detail in shadows AND highlights in your final image are old hands with HDR. What else new could you possibly use it for?
Because most HDR images I see appear to show a lot of detail I started wondering whether this is a feature I could exploit even when I don’t need to capture a dynamic range greater than my camera. My question was whether an HDR image would show more detail than the properly exposed version of the same composition.
To experiment on this I took the easy way out, choosing an overcast day to get the broadest light coverage, picking a subject with lots of details, and shooting with my sharpest lens, a 50mm macro. For my control image I exposed to get as wide a histogram as possible with no pixels blown out or blocked up. My range of five images was +1, +2, -1, -2 stops around the control image. Since I had the images anyway I processed them using three popular HDR tools: Photoshop CS5’s HDR processor, Photomatix Pro, and NIK HDR Efex Pro.
Here’s the control image right out of Lightroom’s RAW to JPEG conversion with no Develop processing applied, along with its histogram:
Lots of information in this image and with a little Photoshop processing I should be able to turn it into an interesting B&W image. But is that the best I can get from this composition? Will more information (images) improve the detail or depth? Here are the final HDR images processed through each software package along with the control shown above. Each HDR image is the default rendered with no changes in controls:
There are differences among the processors with respect to color shift and detail preservation. The Photoshop and NIK processors clearly resulted in greater contrast, both globally and locally, whereas the Photomatix processor appeared to flatten the contrast. With their greater contrast the Photoshop and NIK images appear to have more definition than the control but is there actually more information in the image?
I cropped down to a portion of the image where some fine details were present and examined that area on each image.
Compared to the Control the Photoshop and NIK images appear to have more fine detail but I believe the effect is coming from the enhanced local contrast, not more pixels of information in the image. With a little adjusting in Photoshop, I think I could arrive at the same look for the Control, especially if I take the time to use Layers and Masks along with the Curves controls.
So, whereas HDR is very handy when your composition’s dynamic range exceeds your camera and you want an image that shows details in shadows and highlights, it doesn’t appear to bring any improvements to definition in images that are properly exposed within your camera’s dynamic range. This shouldn’t be surprising – each image only has the pixels delivered by the camera and this particular software isn’t creating any new pixels. Thus, improving definition in this manner can only come from increasing the contrast along edges as there is no new information being added to the image.
Having said that, all these images were the Default right out of the camera and processors. Each of these software packages gives you control of many aspects of the image (you are shooting in RAW, right?) which can be used to accentuate or diminish elements of your image to deliver just the look you want to display. It’s worth your time to play around with them just to get a sense of the range of flexibility you have at your fingertips to pursue your personal vision for images.
Please feel free to comment if you’ve had experience with HDR. Have you performed any of your own experiments in terms using it to improve definition in your images?
Tags | HDR, Mel Mann, technology