Creating a black and white picture from a color
original allows you to change the shot’s emphasis.
For example, a portrait may be marred by strongly
colored objects in view, or your subjects may be
wearing clashing colored clothing. Seen in black
and white, the emphasis in these pictures is skewed
more toward shape and form.
The translation process
A black-and-white image is not a direct translation
of colors into grayscale (a range of neutral tones
ranging from white to black) in which all colors
are accurately represented—many cameras favor
blues, for example, and record them as being lighter
than greens.
When a digital camera or image-manipulation
software translates a color image, it refers to a built-
in table for the conversion. Professional software
assumes you want to print the result and so makes
the conversion according to a regime appropriate
for certain types of printing press and paper. Other
software simply turns the three color channels into
gray values before combining them—usually giving
dull, murky results.
There are, however, better ways of converting to
black and white, depending on the software you
have. But before you start experimenting, make
sure you make a copy of your file and work on that
rather than the original. Bear in mind that
conversions to black and white loses color data that
is impossible to reconstruct.
Before you print
After you have desaturated the image (see box
below), and despite its gray appearance, it is still
a color picture. So, unless it is to be printed on a
four-color press, you should now convert it to
grayscale to reduce its file size. If, however, the
image is to be printed in a magazine or book,
remember to reconvert it to color—either RGB or
CMYK. Otherwise it will be printed solely with black
ink, giving very poor reproduction.
Four-color black
In color reproduction, if all four inks (cyan, magenta,
yellow, and black) are used, the result is a rich, deep
black. It is not necessary to lay down full amounts of
each ink to achieve this, but a mixture of all four
inks (called four-color black) gives excellent results
when reproducing photographs on the printed
page. Varying the ratio of colors enables subtle
shifts of image tone.
All image-manipulation software has a command
that increases or decreases color saturation, or
intensity. If you completely desaturate a color
image, you remove the color data to give just a
grayscale. However, despite appearances, it is still
a color image and looks gray only because every
pixel has its red, green, and blue information in
balance. Because of this, the information is
self-canceling and the color disappears. If, though,
you select different colors to desaturate, you can
change the balance of tones. Converting the image
to grayscale at this point gives you a different result
from a straight conversion, since the colors that you
first desaturate become lighter than they otherwise
would have been.
Saturation screen shot
With the color image open you can access the
Saturation control and drag the slider to minimum
color. This gives a gray image with full color
information. In some software you can desaturate
the image using keystrokes instead (such as Shift+
Option+U in Photoshop, for example).

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