Archive for October 2010

Infrared and “false color” processing   Leave a comment

My photographer friend Esther Duffy asked how it is possible that I am able to come up with versions of the same infrared photo in different colors. So I’m going to do my best to explain “false color” and what it means in infrared photography. Infrared light has no color, because it exists outside the range of visible light, which contains the colors we see. Depending on the IR filter you choose when you convert your camera, you can allow some of the color red, which exists at the end of the visible spectrum before we head into IR, to reach your sensor. Mixing this red light with the IR light allows us to place color in our IR photos. But the color will not match “true color,” which we get when we shoot regular photos because all the colors of the visible spectrum are not available. Other than red, none of the other visible colors are recorded in an IR photo. “False color” is generally color that differs from “true color.” False color has many scientific and tactical uses. An example: in military applications, sophisticated infrared cameras can photograph foliage and based on the amount of light it reflects, render colors that can show the difference between live foliage and dead foliage that is being used for camouflage. To the human eye, it all looks green. But in IR, colors can be rendered based on reflectiveness, and dead foliage will not reflect light the same as live foliage. In more traditional IR photography, “false color” is the result of how we process the image using software like Photoshop. What’s fascinating, and unknown until we get to work, is how the colors will render based on the reflectiveness or absorption of the light.

Above is a digital infrared image as it comes out of the camera. You can see the overall red cast. This is an image shot with a 665nm enhanced color converted Canon EOS 20D and a custom white balance. ( I’ll cover white balance in a future post. As you might imagine, it is quite different than in traditional, visible light photography.)

With my tonal range looking quite healthy, I now move the image from Camera Raw and into Photoshop (above.) I apply a classical adjustment in levels by using the eyedropper to click on a white point and a black point. This is no different than what I do with my traditional, visible light images. This is the result. It is a “false color” image because these are not the colors we would see with our eyes or a regular camera. But I have done no trick photography here. All I’ve done is set the white and black point and the colors were rendered based on the absorption and reflectiveness of the infrared light and the small amount of visible red light.

Now, I move into Photoshop’s channel mixer, which is probably the most popular tool for processing IR images. It is here that we apply the classic infrared “Wood effect,” which I have discusses in prior posts. The first step of a common “channel swap” involves removing all the color from the red channel and replacing it with blue. I select the red channel and set the red slider’s value from 100 to 0. I then change the blue slider’s value from 0 to 100. The result is this very cool pink color added to the highly reflective foliage. Sometimes this step adds a green cast to the darker parts of the image, but it did not here. I call this a “half swap” because it’s just half of the full channel swap process. But many times I will choose to stop here if I really like what I have. If I do stop here, and the image has a green cast, it can easily be removed with the Hue/Saturation control or in curves.

In the image above, I complete the “channel swap” process. I move to the blue channel and reverse the red and blue sliders as I did in the red channel, applying 0 to the blue channel and 100 to the red channel. And there you have it, a typically processed “false color” infrared photograph!

Of course, nothing says you have to process your IR image to a certain protocol. Experimenting is a lot of the fun with digital IR. For the above image, after setting the white and black point in levels, I bypassed the channel mixer and went right to the “Hue/Saturation” control. As I played around with the various combinations by adjusting the sliders, I noticed that only the reflective foliage, and not the rest of the image, was changing colors. I settled for this interesting green.

And if wild and crazy is your style, feel free to, as the legendary baseball announcer Jack Buck once said, “Go crazy, folks. Go crazy.” It’s not my thing, but it just might be yours! Experiment, play, explore, take chances. Have fun!


Seeing anew, part of the fun!   Leave a comment

One of the coolest things about digital IR is rediscovering scenes that you’ve taken for granted or never given much thought to. I’ve driven past Pyramid Lake between Bakersfield and Los Angeles hundreds of times during the past 30 years, but never stopped to photograph it. I don’t like to shoot pictures that have been taken hundreds of thousands of times by other people, and I can guarantee this is the case for Pyramid and it’s wonderful view right along Interstate 5. How many people have snapped the scene from the passenger side window as they zoomed toward the southland? On this day, I loved the cloud formations and the stormy weather, so I drove off the interstate, took  a pretty short walk to hopefully get a vantage point a little different than what most see, and took this shot. Camera was my Canon EOS 20D converted to enhanced color 665nm, 20 mm Canon lens with a polarizer. I decided to bypass the color opportunities here and went with a black and white version.

Another scene that has always intrigued me is the Fairfax Grange, a small country dance hall on Bakersfield’s rural eastern edge. I am struck by how the grange seems to be in competition with the symbols of a city’s encroachment as it continues to grow and expand with seeming abandon. I imagine this little country grange, which once had this intersection all to itself, will soon be surrounded by new housing or industrial developments. I think the ability of IR to make dramatic statements, emphasizing the starkness of the scene, comes into play here, particularly in its rendering of the sky and clouds. Camera was the same Canon EOS 20D converted to 665nm enhanced color IR, but I opted for full black and white. Lens was a Canon 24-70mm f2.8L.

The Wood effect in IR photography   Leave a comment

A big part of the allure of infrared photography is the surreal, other-worldly look that photos take on as they reflect or absorb IR light. The “Wood effect” is probably the most desired effect among IR photographers. It is the effect which turns green foliage, like trees and grass, white or near-white, depending on your choice of conversion. It has nothing to do with wood, but is instead named after the American physicist who discovered it, Robert Wood. Unofficially considered “the father of ultraviolet and infrared photography,” Wood discovered the reflectiveness of chlorophyll, a primary component of foliage, when photographed under infrared light. The “Wood effect” allows photographers working in IR to create dream-like landscapes, to make regular, visible light scenes look like winter wonderlands, or to allow creative photographers to explore new ways of seeing that are simply not part of the visible spectrum.

Below is an example of a “winter” look resulting from the “Wood effect.” This is actually the Village of Arroyo Grande on California’s central coast. It never snows in Arroyo Grande. This is a color and black and white version of the same shot, produced with a Canon EOS 20D converted to 665nm enhanced color infrared. The images underwent minimal processing, just a standard white and black point set in Photoshop’s levels, then a red/blue channel swap for the color version and a monochrome conversion in the channel mixer for the black and white version.

Capturing motion with a converted camera   Leave a comment

Here is perhaps the most compelling reason to go with an IR camera conversion rather than using external IR filters. With a converted camera, you can stop motion since the camera works virtually the same as it did before the conversion. This is not possible with external filters. You can’t achieve a shutter speed fast enough to stop the action, and in most cameras, you won’t be able to see your subject in the viewfinder because of the super-dark filter. This was shot in the coastal community of Los Osos, California. I saw the great egret flying around the bay, switched to my Canon 70-200 f2.8 L which performs flawlessly with Canon 20D converted to 665nm enhanced color infrared (even though the camera was calibrated to focus with my 24-70 2.8 L) and waited for it to fly by me. I just don’t think this shot is possible without a converted camera. The image underwent my standar IR processing method, with a white point and black point set in Photoshop’s levels, then a red/blue channel swap in the channel mixer.