I recently completed an assignment that required a High Dynamic Range (HDR) final image. This image blended an outdoor background with a studio foreground subject. Both were processed using HDR capture and develop techniques. I think the result turned out well, don’t you?
HDR has experienced a surge of growth with amateurs and pros alike since its invention. HDR was first conceived in the mid 1850’s, but the equipment was not available to produce it. Dodging and burning (selectively increasing or decreasing the exposure of a photograph in the darkroom or on the computer) stood in for HDR until the late-20th century. One-key-press HDR is now available in mainstream Lightroom/Photoshop software and through third party plugins such as HDRSoft’s Photomatix. Some pros have made their reputations on their unique applications of HDR (example: Joel Grimes).
Why do we need or want HDR photographs? The range of light available to the human eye (from infrared to ultraviolet and beyond) far outweighs our ability to see it. Similarly, we are less astute than the average house cat at seeing shadows and dark tones. Nonetheless, our eyes do have a dynamic range of about 22 f-stops of light, which compared to the average DSLR camera, is about 4 fold more (5 stops in the camera). So, one argument for using HDR processing is simply that it will bring the highlights and shadows (the range of luminance in the image) more closely into alignment with what the human eye can see and more closely into alignment with the actual scene.
That said, it seems the monitors on which we display the images and the printers on which we print them don’t have a range of tones that corresponds with the HDR values we might want to assign. Monitors and printers will apply “tone mapping” to try to map the tonal range to something they can handle. The process actually reduces the overall contrast of the image as defined by the HDR values selected. So, at the end of the day, we’re still left with something less than the ideal 22 f-stop result.
HDR imaging wasn’t even possible for the average photographer until cameras were sophisticated enough to capture sufficient detail in a very wide range of exposures (low and bright light) and software/computers were powerful enough to bring all of the data together into one file. Today, auto exposure bracketing makes it simple to capture the images – my Canon will capture up to 7 different exposures in a single pass. Again, push two buttons and it’s ready to go.
Once captured, the images are imported into a special option available in either Photomatix or Adobe Lightroom and various choices are made in the menus and sliders to get just the right look. Even with one-touch processing, the ultimate value of an HDR image is in the personal skill of the artist, ensuring that every pixel has just the right amount of “luminance”. The artist also has to guard against unwanted results, such as increased noise in the image. The best can find just the right balance.
I do think HDR has its place in outdoor situations with natural or man-made landscapes. I’m less convinced that it’s needed in portrait or indoor applications. Hopefully over the next few months, I’ll discover its best use for my images, probably just about the time that the fad will die away…Timing is everything in this business. That’s a topic for another day.
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