Channel,toinfluencejustoneofthesethreecolours.You’ll
find this less valuable than the default setting, but you might
occasionally find instances where it’s useful.
Dodging and burning
The actions we’ve covered so far are ones that affect the
complete photo, but it’s also possible to make changes to just
parts of the scene, and this is really useful in some cases. A
classic example is darkening the sky to make it look more
dramatic, although there are also instances where lightening
certain areas of the scene is required. Of course, there’s little
point in attempting to darken areas that are a uniform white,
or darkening that are uniformly black, because additional
detail won’t emerge.
The techniques for achieving this are called dodging
(lightning) and burning (darkening), the words originally
referring to methods that were used in photo printing in the
darkroom, back in the days of chemical photography. In
passing, you might think that the names of these two actions
are counterintuitive – surely burning sounds like it ought to
make an area lighter – so here’s how to remember. It’s all tied
up with the fact that photographic printing was a negative
process, in creating a positive print from a negative film.
The process of burning involved shining a narrow beam of
light, by hand, onto the photographic paper while the image
from the negative was being projected onto the paper by the
enlarger. Since printing worked in reverse, this caused the
area that was additionally illuminated to become darker.
Dodging, involved using a small opaque object to interrupt
the light in a small area between the enlarger and the paper,
thereby making it lighter.
GIMP has a combined tool for dodging and burning, which
you’ll find at Tools > Paint Tools > Dodge/Burn, but this is not
ideal, except for use with very small parts of the image. The
snag is, if you want to lighten or darken a large area, unless
you want it to take forever, you’d start with a large tool to
dodge or burn most of the region, and then switch to
progressively smaller tools to accurately define the edge
of the area.
Having changed the size of the tool, unless you’re
extremely careful, either you won’t quite meet the portion
you’d dodged or burned with a larger tool, or you’ll overlap it,
resulting in the overlap being dodged or burned twice. In
either case, you’ll end up with a line along the joint. The
method we describe here avoids this problem.
We’re going to use a new layer to define the lightening and/
or darkening, so select Layer > New Layer. Now, in the Create
a New Layer dialog box, name the layer ‘Dodge/Burn’ (this
isn’t essential but it’s helpful if you end up with lots of layers),
select Overlay as the mode, set Opacity to 100%, and fill the
layer with 50% grey. The way to do this is to choose 50% grey
as the foreground colour using the Colour Selection dialogue
(the large icon that looks like two overlapping sheets of paper
in the toolbar – you can do this without closing the Create a
New Layer dialogue) and then, in the Create New Layers
dialogue, select ‘Foreground color’ against ‘Fill with’.
Except for the fact that the new layer will appear in the
Layers tab, so long as it’s displayed, nothing should change.
However, if you now select the Dodge/Burn layer, as indicated
by it having a white border on the Layers tab, anything you
paint in a shade of grey that’s lighter than 50% will be
lightened, and anything you paint in a shade of grey that’s
darker than 50% will be darkened.
You’ll soon learn what shades of grey to use – in fact you
can use several degrees of dodging and burning on the same
layer, and you can over-paint with different shades if you
subsequently change your mind. Critically, though, because
you’re only ever painting in a single colour, rather than
applying an effect, the problem with using the Dodge/Burn
tool doesn’t apply.
Having used GIMP’s layer functionality for the first time, a
brief word on saving your work is appropriate. Although your
original image was probably a Jpeg, you can’t save it as a Jpeg
and preserve the layer structure. Instead, you should save it as
a XCF file, which is GIMP’s native format. Now, when you
reopen it, your individual layers will still be viewable and
editable, and when you eventually need a Jpeg file, you can
do this by exporting it in that format.Horizon straightening and cropping
If the horizon isn’t straight it would be good to correct that
first because the process of straightening the image will then
require the image to be cropped, which is our next topic.
Though if it’s a long way from horizontal, it would have been
preferable to have taken a straight photo initially.
Straightening the horizon makes use of the Measure tool,
so select the tool that looks like a pair of compasses in the
toolbar. Next, ensure that the Tools Option tab is displayed.
Now, click on the horizon at the left side of the image and
drag a line to the right edge of the horizon. The angle of that
line will be displayed, and if you click on Straighten in the
Tools Option tab – which will have Measure as its title – it will
rotate the image by the measured angle so it’s horizontal.
However, things differ slightly depending on whether you
want to follow this up with additional cropping. If you do, just
select Clip against ‘How to clip’ (you’ll see this title when you
hover over it) before straightening. If you don’t want to crop
further, select ‘Crop with aspect’ instead, and then afterBlackandwhitephotoscanlookverydramatic.We’llleave
you to learn which subjects really lend themselves to this- although scenes with lots of contrast and texture often
look good – but we will provide a bit of guidance on
converting a photo to B&W. This suggests that you
should always shoot in colour, and that’s undoubtedly
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The simplest method is to select Image > Mode >
Greyscale. This might provide an acceptable result, but
it’s very similar to what your camera would do if you
shoot in B&W, and offers no options. It considers all
colours as equal, so the end result might exhibit poor
contrast. Since good B&W is often high-contrast photo,
you could do better by carrying out a conversion that
takes account of colours.
B&W landscape photographers often aim to darken
blue skies to provide high contrast between the sky
and the clouds. One way to achieve this is to extract just
the red component of the photo, which you can do by
selecting Color > Components > Extract Component. In
the Extract Component dialogue box, choose RGB Red
as the component. Because blue skies contain very little
red, a bright blue sky will be rendered almost black.
BLACK AND WHITE CONVERSION
Selecting just the red components is a good way of converting a colour photo
to black and white while producing a high-contrast sky.
46 |^ |^ March 2020