Thursday, August 16, 2007
In this first in a series of columns about digital black-and-white, we explore some of the fundamentals
Many Ways To Convert
There are many (too many) ways to convert an image from color to black-and-white. Here are a few:
1) Grayscale conversions eliminate all channels but one. (This defaults to 59 percent green, 29 percent red, 11 percent blue; this can be customized by targeting a single channel before conversion to get 100 percent of any channel in any color space, including Lab.)
2) Desaturate or use the Saturation slider to make all the channels the same without control over the mix.
3) The Channel Mixer set to Monochrome allows you to customize the mix of channels.
4) Using dual adjustment layers, one for Channel Mixer and another (Hue/Saturation or Selective Color) to change color values before neutralization, allows selective conversion based on hue.
5) Use RAW converter settings for both Saturation and Calibrate or Black-and-White functions. (Converting RAW files into Smart Objects allows you to readjust the conversion settings in the future.)
6) Calculations mixes channels using blend modes, best for industrial-strength applications.
7) Channels as layers give you all of the above and the ability to use Blend If sliders, but with a more complex routine and file structure and a larger file size.
Masks can be added to all but the first option to make conversion selective.
All of the methods blend channels, in various combinations and then equalize them, before or after modification; in an RGB file, if the values in all of the channels are equal, then the image will be absolutely neutral (or black-and-white).
While all methods may work reasonably well, some consistently work better than others. The method that offers the ultimate in control (turning channels into layers) is complex. In many cases, simpler methods do equally well. But which other option should you choose?
Here are a few criteria to weigh:
1) Power and precision. Get the control you need to get where you want to go.
2) Flexibility. Favor methods that offer the flexibility of being able to change any aspect of a conversion at any time in the future, including returning to the full-color version. In Adobe Photoshop, use adjustment layers or layers. When using Adobe Camera Raw, open images as a Smart Object.
3) A good preview. View before and after states simultaneously to help you make more informed decisions.
4) Easy to use. When faced with multiple options with equal functionality, favor the simpler one.
5) Simpler file setup. Apply the KISS principle whenever possible.
6) Leaner file size. Smaller files are faster and easier to store.
While this is my preferred ranking of these criteria, you'll want to modify these according to the needs of a given situation.
A Good Preview
A good preview of both the before and after states of an image is critical to making informed decisions. The easiest way to do this in Photoshop is to duplicate the file and use the duplicate to preview the color data throughout the process. If you'd also like to be able to see the separate channels side by side for simultaneous comparison, duplicate the duplicate file and use the Split Channels feature located in the Channels palette submenu. (This feature works only for flattened files, so flatten the duplicate before trying it.)
In the next issue of DPP, we'll explore more conversion techniques as we continue the (R)evolution series on black-and-white.
A member of the Photoshop Hall of Fame, internationally renowned fine-art photographer John Paul Caponigro is the author of Adobe Photoshop Master Class. He teaches an array of workshops in his private studio. Get more than 50 free PDFs and test files, including techniques related to this article, at www.johnpaulcaponigro.com.
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