Well it really doesn't matter much any longer,
especially if using Photoshop, since changing from colour to monochrome
is simply a matter of a few Mouse clicks and bingo! The most obvious way
to get black and white from colour in Photoshop is simply to do a mode
conversion from the menu bar - "Image > Mode > Grayscale", this
will discard all colour information. Personally I find this method
produces rather flat images that require quite significant amounts of
post scan adjustment in Photoshop. However, a better option exists in the
form of "Channel Mixer".
A printer friendly version of this tutorial can be
downloaded by mouse clicking the following icon
.
"Channel Mixer" is a very useful image
adjustment tool that allows the user to mix/blend the colour channel
balance of an image. In fact so powerful is this tool that we can easily
replicate the effect of placing red or yellow filters over the lens when
using black and white film. Enough of the waffle, let's get on with the
method.

Advertisement Pillar, Berlin - a pretty ordinary
record shot, lets see if we can make it better!
The starting point will always be a full colour
image in RGB mode. Most film scanners will find capturing the full range
of colours, etc. pretty easy, but had the original been in black and
white it's usually a different matter. The image above is the raw scan
imported directly into Photoshop via my Nikon LS30 film scanner using
LaserSoft SilverFast software.
The following steps will take us though the process
of creating a simple black and white image, followed by a sepia toned
image and finally we will create split toned image.
The Process: -
Step 1 - Channel mixer
set-up
-
In Photoshop open a full colour RGB image as per the
above example
-
From Photoshop menu bar select "Layer > New
Adjustment Layer > Channel Mixer"

-
Make sure "Monochrome" is selected.

Channel Mixer Dialog
By selecting the "Monochrome" checkbox we
are instructing Photoshop to convert the full colour RGB image into a
monochrome preview, but the image still retains all the colour channel
information. Note that in the above screenshot of the "Channel Mixer"
dialog that the "Output Channel" is Gray; we cannot change
it. However, even though the red channel is initially at 100% and the
green and yellow channels are at 0% we are free to mix them as we see
fit. The objective is to optimise the image whilst ensuring that total
percentage for the three channels adds up to 100% or as near as is
possible. Interestingly combinations adding up to more or less than 100%
will be either darker or lighter than the original colour image. So don't
be afraid to experiment!

This image is
rather flat, and the separation between the mailbox and sky is poor
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