RGB 2 B+W; Conversion Strategies For Tonal Control

Every digital image starts out as a color image, an RGB that, when shot in Raw format and loaded as a 16-bit file, contains millions of color and brightness codes. These codes, or pixel addresses, can be manipulated in many ways using presets or “manual” adjustments to create looks that range from “true” to highly stylistic interpretations of the content within the image. Exploiting this malleability, photographers can now have black-and-white tonal control over each image even before delving into Curves or Levels and/or burning/dodging tools; in fact, using color conversion tactics previously required tonal controls and selections often became unnecessary.



Color conversion is about selecting the grayscale tonal value you want for colors in the image. This photo of rock formations (A) can be interpreted in many ways. Here (B) is “straight” desaturation or conversion by software opinion of this shot. Not bad, but there’s so much more you can do with the images by working with the color conversion options. Here (C), the blue is made into a darker tone and the red, yellow, and orange lightened by working the Grayscale Mixer in Lightroom. This eliminates the need to select the sky and usually eliminates any haloing a selection might cause.
All Photos © 2010, George Schaub, All Rights Reserved
When you open an image in a Raw processor, such as Adobe Camera Raw shown here, you have the choice of selecting the bit depth of the image, here 16 bits. Higher bit depth means more image information, better quality, and more choices when processing.

This tactic is an extremely enhanced version of using filters over a lens when exposing panchromatic film, in that you can create highly refined filter combinations to attain the desired effect. For example, to emulate the look of a red filter when exposing panchromatic film, choosing the red filter preset will deepen blue and green, leading to a stark, deep sky and often rendering green-colored subjects as silhouettes. However, you can also choose to boost the yellow and orange color tonal conversions in the image in ways that using a red filter alone could never achieve.

Here are a few Grayscale Mix options in Adobe Camera Raw of a shot made at the Albuquerque Balloon Festival (A). Here’s the shot as it opened with the accompanying Grayscale Mix panel that served as the default (B). This panel (C) shows the adjustments that resulted in this image (D). Note the light interpretation of reds and the darkening of blues. In this panel (E) the opposite tack has been taken, resulting in a dark rendition of reds and light rendition of blues and greens (F).

You can set the “basic” monochrome filter effects in the camera prior to exposure, but this will not allow for nuanced control. However, this “immediate” post-exposure processing has its uses, especially when the photographer wants to previsualize the effect and “see” how the processor will handle the image as a monochrome in Live View mode. This ability—to see in black and white prior to making the exposure—is a very new breakthrough for photographers and photography, something I think we might take for granted these days, but which not too long ago required a keen, experienced eye and the use of viewing filters and other tricks. In essence, previsualization is now easily accomplished by just knowing how to program the camera software and by having the ability to see the “final” image prior to exposure in a Live View setup.


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