Darkness into the Light
One of the great frustrations of photography has always been the limited ability of film—and to a lesser degree, digital camera sensors--to see what’s in the shadows without making the highlights unusable, “blown out”. Color images in particular were a problem, I’ve recently been frustrated by trying to get a good scan of a back-lit 962 at Sebring from back in the day. The Kodachrome was happy with the exposure on the white part of the car, but the shadowed red side toward the camera was lost in the murk.
Well, Kodachrome is history, and I lament its departure a lot less than many photographers. The top-end digital cameras can now see a lot further into the shadows than their predecessors. That’s a good thing, but it doesn’t completely solve the problem. Without some additional magic that’s not yet automatic, the darkest and lightest parts of an image may not be visible when your image is printed out, and certainly not if it’s run through a printing press on the way to the viewer.
On the left is the better of two dark, handheld exposures, neither usable as they came from the camera. On the right is the more satisfactory HDR photorealistic combination of the two.
Getting a bit wilder with the HDR settings, darkened sky, and aggressive contrast modification produced the left-hand image. On the right is the full Harry Potter effect. You just know that if your eyeballs ever see this out there in the natural world that the space squid vampires are on the way in.
That’s where HDR (high dynamic range) imaging comes in. This is a software solution to balancing the dark, light, and midrange parts of an image in a different way, and delivering them into a range that can be handled by a monitor, a printer or a printing press. With the right input, it will work with any camera, film or digital, old or new.
With an older digital camera or scanned film, you should have multiple images shot at different exposures; 3 shots one f-stop apart on either side of the metered exposure will usually do the job, but as many as 6-8 are sometimes done. The software then combines these, using the overexposed images to get information from the dark part of an image, and the underexposed to make sure that the brightest parts are showing detail. Problems: you have to realize that you may want multiple exposures when you make the shot and they really should be shot off a tripod for perfect registration, although I’ve had good luck with high speed motordrive working with automatic bracketing.
Earlier versions of Photoshop had HDR software incorporated, but it didn’t work really well until the current CS5 version, and many people relied on independent manufacturers for their needs; I’ve used both CS5 and Photomatix Pro (www.hdrsoft.com) with good effect; the latter software comes with a pretty good tutorial to get you up and running with the many controls. What has been disappointing to me is scanning old film images at different exposures and then trying to recombine them; if the information wasn’t there in the old Kodachrome, it’s not manufacturable.
Not too bad straight out of the camera, but the 904’s tires have disappeared into the dark, and the red 935 is way dark. Using the HDR toning feature of Photoshop with this single exposure gives a reasonably believable picture of the 904, but look at the candy apple special of a 935—too much!
There is also a little-known filter in CS5 that produces a somewhat similar effect with a single image; image>adjustments>HDR toning can produce some very nice effects with a single exposure image from a newer, high sensitivity sensor digital camera, and may at least perk up some older scanned images. A similar outcome can sometimes be had with image>adjustments>shadow/highlights, which can bring up the shadows if you have good mid range and highlights; this is often a more subtle effect.
HDR is detested by some for what is considered its signature “look”, which is a little hard to describe, but often consists of emphasis in some details and some color shifting. But I tend to limit my purist leanings to things Porsche, and would note that there are many different HDR looks, depending on processing, right on up to what has been called the “Harry Potter” effect, clearly not something produced by an unmolested linear sensor. Any look-at-me effect tends to have a limited shelf life; think of fish-eye images, oversaturated color, or images over-sharpened for effect. All can be good at times, but a diet of only chocolate ice cream isn’t a good thing.
Overhead lit F1 engine makes brightwork too light, and shadowed painted features invisible. On the left is the HDR toning solution (using single image); on the right is an image made using the shadow-highlight tool to bring up the dark areas. Which do you prefer?
That said, I’ve been seeing a lot of HDR toning lately, including a considerable amount from Porsche’s graphics guys. These images can be very dynamic, and can be presented with varying degrees of subtlety depending on how the software is used. There is also the possibility of blending an HDR image back with some parts of the unmodified image for a different or softer effect; Photoshop’s generally useful edit>fade filter doesn’t work here, nor can it easily be done in layers in my experience. What works is to use the history brush and paint over the HDR image with some percent of the unmanipulated image.
Bottom line for me is that HDR toning can bring out important shadow information, save a weak or flat picture, sometimes help save an underexposed image, and can provide coloration and image detail that adds a lot of impact. I find myself using it more and more; perhaps you will too.
Thanks for reading, and as always - give it a try, and let me know what you think. I'm firstname.lastname@example.org.