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Monday, June 23, 2008

Use Adobe Raw For B&W

Using the tools in ACR, you can work more efficiently and take advantage of RAW controls to make your black-and-white conversions

This Article Features Photo Zoom


Adobe Camera Raw offers a number of powerful controls for converting a color image to a black-and-white or split-tone image. Working from Bruce Fraser's original, Real World Adobe Camera Raw With Photoshop CS2, Jeff Schewe has updated the book, and a new version will be available this summer. In this article, we walk you through some examples of how you can take advantage of Adobe Camera Raw's black-and-white conversion tools. We look at the HSL/ Grayscale Panel and Split-Tone Panel, as well as show the steps we went through to take an image from color to black-and-white.

The HSL/Grayscale Panel

The HSL/Grayscale panel (which you access by pressing Command-Option-4) has three separate subpanels, which can then transform to yet a fourth panel at the click of a button. Depending on which mode you're displaying, Color or Convert to Grayscale, up to 24 separate sliders are in play. With all these controls, you might expect the HSL portion to be a complicated beast to manage, but it's not. It's rather simple, yet incredibly powerful and far more useful than the Basic Saturation control.

The HSL Controls. As you can see in Figure 1, the colors under control aren't the typical additive and subtractive primaries of red, green, blue, cyan, magenta and yellow. The elves who work on Camera Raw and Lightroom decided to throw in a twist by choosing color controls that are more useful for photographic correction than the primaries. And for good reason—the colors in nature will often fall in between the spectral primaries, a fact that makes control of those colors more difficult using only the primaries.

RIGHT: “Hamish” shown as the result of auto black-and-white conversion. BELOW: The same image with the green slider set to -100. BOTTOM: The same image with green set to +100.




Hue. The Hue control lets you “tween” a color between two related hues. Thus, red can move toward magenta (cooler) or toward orange (warmer). Each of the hues in the panel can have a useful impact on fine-tuning the exact color rendering the RAW processing can deliver. While Hue is conceptually similar to the controls in the Calibrate panel, you shouldn't confuse their intended use. The Hue sliders are intended to correct photographic or “memory” colors, while Calibrate is intended to correct technical rendering of the spectral response of your camera. That said, you're free, of course, to use whatever tool catches your fancy.

Saturation. Saturation controls, well, the saturation of the target's hue. You'll note that on each of the HSL subpanels, there's a Default button, which is grayed out since there currently are no adjustments. Once you move a slider, it's enabled. Since there are three separate panels, the designers decided it would be useful to include a Default button so you could reset all the controls for that subpanel. It's quicker than going through all eight sliders per panel to reset them.


3a) 3b)
Luminance. The Luminance subpanel is the source of a lot of color and tone adjustment that may augment and improve on the overall tone mapping using Basic and/or Curves. Say, for example, the overall tone mapping is fine except that one particular color is too light or too dark in the resulting tone curve. It's simple to grab the slider for that color and lighten or darken it without affecting the rest of the tone mapping.

The Grayscale Controls. I've taken the liberty of making Bruce's “Hamish” image grayscale. When you click the Convert to Grayscale check box (Figure 2), the panel is transformed to the grayscale conversion panel with the ability to choose how certain colors convert to color. Think of this as an infinitely variable “panchromatic response” filter for your images. Unlike in the old days, when black-and-white photographers would shoot with color contrast filters over their lenses to alter the color rendering of their black-and-white film, we can now exercise far more power and control by adjusting sliders






The same sets of colors are represented here as in the color version of the panel to allow you to fine-tune the tone rendering for various colors. As shown in the two images in Figures 2a and 2b where the green slider is set to -100 and +100, the control allows the greens in the image to be made very dark or very light.

Auto. Clicking the Auto button performs an automated adjustment of the color settings to optimize the conversion to grayscale while trying to preserve a tonal separation between colors. It's often the case where two colors have considerable color contrast, but upon conversion to grayscale, they end up with almost the exact same grayscale tone. The Auto conversion tries to optimize the separation of colors to tones. In general, it's often close—so close that, many times, all that's needed is a couple of slider tweaks to finish off what Auto started.





The Split-Tone Panel
With only five slider controls, the Split-Tone panel (Command-Option-5) is Camera Raw's simplest set of controls. Some users may think of this panel as a one-trick pony, but its usefulness would prove otherwise. Although many use the options on this panel only for grayscale conversion and to re-create chemical split-toning, the adjustments can be used for color images as well. The functionality is simple (Figure 3); you select a color hue and a degree of saturation in either Highlights or Shadows or both. Then, depending on the area you want to use as a balance point, you can adjust the Balance to bias the adjustment split lighter or darker.

Converting An Image From Color To B&W
In the image shown in Figures 4 and 5, which Jeff shot at Bryce Canyon National Park in Utah, the object is to color- and tone-correct the image and then convert to black-and-white. Jeff shot the image with a Canon EOS 10D with a 17-35mm lens at 20mm.



Image Evaluation. The image is just really underexposed, so we had to take all that data in the shadows and move it way to the right (Figure 4). Image Edits: Tone. First we increased the Exposure and then the Brightness and Contrast. We also added some Clarity (set to 90), partially in preparation for the eventual conversion to black-and-white (Figure 5). Image Edits: Conversion. When making color-to-grayscale conversions, we try to see what Camera Raw will come up with on its own (Figure 6). In this case, Camera Raw did a decent job, but we wanted to darken the sky a bit more by pulling down the blues. We also wanted to darken the oranges to keep some additional detail in the distant cliffs while lightening the yellows (Figures 6a and 6b). Then we used the Parametric Editor of the Tone Curve panel for additional tone mapping to adjust the postconversion distribution (Figure 6c). Figure 7 shows the final image and resulting histogram.

In some cases, Adobe Camera Raw's tools will do everything you need to make the image right. Other times, you'll find that Photoshop is still required to fine-tune some aspects. ACR's power lies in making global changes to the image, while Photoshop gives you the freedom to isolate and control specific areas and tonalities. Using ACR to do the initial black-and-white conversion will often make your later Photoshop adjustments much more efficient and effective.

Bruce Fraser and Jeff Schewe are the coauthors of the Adobe Press book Real World Camera Raw with Adobe Photoshop CS3 (Peachpit Press). Fraser was an internationally recognized authority on digital imaging and color image reproduction. He coauthored the best-selling Real World Adobe Photoshop, as well as Real World Color Management. He was a principal and founder of Pixel Genius LLC. Schewe is a pioneer in the field of digital imaging and an alpha tester and feature consultant for Adobe. He has worked closely with Thomas Knoll, the founder of Camera Raw, since its first development. Schewe teaches and consults with leading companies; he's a principal and founder of Pixel Genius LLC.


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