(Editor's note: This article was originally published in July, 2006, and is being featured again with its original content.)
As a wildlife and landscape photography enthusiast with a couple of years of serious digital shooting under my belt, I do not claim to be an expert with High Dynamic Range (HDR) imaging or photography in general. But I have fun in the field, enjoy learning as much as I can about the art and science of photography, and have produced some images that are personally rewarding, as well as enjoyed by others. I currently derive particular satisfaction from working with stitched panoramas taken at sunrise or sunset, printed on roll stock.
Table of Contents (download PDF version - Warning! 10MB file)
Late in 2005 I began adding HDR processing into my workflow. This was done to gain greater access to the tonality present in wide and dramatically lit vistas. I mostly bypassed the usual digital exposure blending route as it seemed labor intensive, although I know the technique can produce results. Naturally I posted several HDR images to Naturescapes.Net (NSN), and several people expressed interest in the technique used to create these images. At the request of the NSN editorial team, I organized my learning and thinking about HDR, and this article is the result.
For at least a few of those who read this, I hope for two things. First, I would like to add some fuel to your own creative fires in working with HDR images. Second, I hope you will post your results and share questions, ideas and techniques that work for you. There is still much to learn as this new imaging capability, its tools, and our creative use matures.
Say I have an image that looks like this:
I captured the image at sunrise, a great time to be out in the field. My senses soaking up everything before me, I tripped the shutter, hoping to capture an image that would evoke wonder and appreciation – a hint of the moment.
Back at my workstation, I eagerly began sorting through the captures. However, despite the presence of a fair amount of dramatic light and lots of interesting tonality and detail across the original scene, images like the one above just do not evoke the experience. The clouds lack drama, detail and color; portions of the sky are far over-exposed; distant trees have turned to a muddy blur; and the ice does not reveal the snappy surface detail it showed in the early morning glow.
Of course, I realized while out shooting that there was a lot of contrast (or “dynamic range”) in the scene, and that the camera could only capture a small subset of that range. So I shot different exposures (“bracketing”), some optimized for the sky, some for the foreground ice, others for the far, shadowy trees. Not surprisingly, none of these single images really grabs me upon review.
I considered that I could use a graduated neutral density filter in situations like this. At capture time, these filters are used to block some light in the brightest part of the frame, often the sky. This effectively expands the captured dynamic range by one to three stops. Of course that does not help now, with images that I have already taken. And considering the irregular line of the mountains and the dynamic range reflected across the ice and water, I am unsure if filters would be workable for this scene.
Using an exposure blending technique, I could combine several digital files with different exposures of the scene. It seems worth trying, so I put in some effort with three exposures taken across a 4-stop range using automatic exposure bracketing. The images are layered, luminance masked and blended in Photoshop CS2, together with some curves and contrast enhancements. This produced the following image:
This is a definite improvement, and with more work I could fine tune this image further. For example, some ghosting in the moving clouds could be cloned or masked out, more work with contrast and curves could increase the drama in the clouds, some selective saturation or white point adjustments could improve the whites of the ice and snow, and so on. The exposure blending technique is used to good effect by many photographers, but it can mean a lot of work. And I feel it will leave me wanting more from this image.