|This image from our masthead began as a long-exposure image shot in the middle of the night. Converting it into a usable image involves a simple, yet time-consuming process.|
This image was shot at about 11:30pm. The light source is a streetlight just off the left side of the frame. The streetlight, as well as the other houselights next door, cast a tremendous amount of illumination on the tree and the house. Thanks to the low noise response of the EOS 10D, shooting a long-exposure image allowed me to get a good exposure with very little noise.
However, as with any long-exposure, low-light image, there’s not a lot of color information in the picture. What’s more, the camera’s auto white balance feature doesn’t really know what to do when shooting in the dark, so the color temperature of the image is completely wrong. The ideal solution would have been to shoot raw, so as to be able to control the white balance later. Embarrasingly enough, I was low on storage and couldn’t fit a raw image on what was left of my card! This is one of those problems that you can always throw money at, in the form of buying more storage, but not in the middle of the night, so I shot a couple of high-quality JPEG frames instead.
Shooting raw would not have solved the lack of color problem, though, so I didn’t loose too much flexibility by having to shoot compressed. Because I knew that shooting a long-exposure low-light image was going to be colorless, my intention from the beginning was to hand-color it later. The idea was to create what looks like a daylight photo, but with very "off" lighting.
For this tutorial we’ll be using Adobe Photoshop The steps shown here will work in any version of Photoshop that supports layers, including Photoshop Elements. (Click the link to download a free time-bombed demo.)
Because the color image in this information is useless, our first step is to discard it. Though there are many ways to convert a color image to grayscale, for our purposes here we don’t need to be too picky or discerning, so a simple Image>Mode>Grayscale command works fine. Photoshop will discard the color information, leaving us with a grayscale image.
However, a grayscale image is just that: grayscale. It can’t contain any color information, and our goal is to paint color information into this picture. So, before we can continue, we need to convert the image back into a mode that will accept color data. Choose Image>Mode>RGB Color. This puts the image back into an RGB color space. Why does it still look grayscale? Because Photoshop discarded all of the data that actually denotes color. Just because you converted it into a space that can allow color, doesn’t mean that it suddenly has any idea what color things should be.
The coloring technique we’re going to use is very simple to implement. Using Photoshop’s Layers menu, create a new layer above our base, grayscale layer.
Next, click on the new layer to select it. In the upper left area of the Layers menu, there’s a pop-up menu that says Normal. This is the Blending Mode selector. When layers are stacked on top of each other, you can change the way Photoshop determines how the pixels in each layer blend together. The default, Normal mode is for higher layers to simply over-write lower layers. To color this image, we want to change the blending mode so that colors in the upper layer blend with the colors in the lower layer.Select the Blending Mode pop-up menu and change it to Color.
We’re going to begin by coloring the bark of the tree. Select Photoshop’s Brush tool, and pick a brown color. Begin painting over the trunk of the tree. As you paint, the brown paint that you’re painting into the upper layer will be combined with the grayscale pixels in the lower layer.
What we have done is separated the luminance information from the color (chrominance) information. The lower, grayscale layer is serving to control how bright or dark a pixel is, while the upper layer is controlling the color of each pixel.
That is basically the entire technique. From here on out, you simply pick more colors and paint accordingly. Note that, if you need to switch back to a previous color, you can’t simply use Photoshop’s eyedropper tool to select the previous color from within the image. The color in your image is not the color you were originally painting with. It has been mathematically altered into a new value. This new value is what Photoshop’s eyedropper will select. So, if you need to re-sample a color you’ve already used, change your upper, color layer back to Normal blending mode, sample the color, then change back to Color and keep painting.
Because you’ve got discreet layers for your color and luminance information, you can perform corrections and adjustments to each layer separately. For example, for our final image, we added some sharpening to the lower, grayscale layer, as well as applying a Levels Adjustment Layer to improve that layer’s contrast. For printing, we used a separate Layers adjustment for our color information. Our final Layers palette looks like this:
Note that I duplicated the background layer and applied sharpening to the duplicate, so that if I want to change the sharpening amount later, all I have to do is trash the Sharpened layer, re-dupe the background layer, and start over.
When all’s done, the final image:
There is a gestalt design concept that states that the human eye is inherently accustomed to having a light source originate from over one’s left shoulder. In addition, the eye is not used to seeing color at night. Because we have colored this image, it looks like a daylight image, yet the sky in the background is dark, and the light is coming from a completely un-natural direction. Together, these two factors create an image that looks slightly askew – hopefully in an interesting way.
Click on Before & After in the main navigation bar for more B&A tutorials. If you’d like to submit an image for editing, please drop us an email. (Soon, we’ll have a more sophisticated submission system).
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