In a moment, some details about using each of the tools,
but first some general comments:
Don't forget to set feathering and antialiasing before you use each tool, as explained in
the Selections page (click 'Up' above). Before you the lasso
or scissors tool, it's a good idea to zoom in
(press + on the main keyboard) as much as you can while making sure
that all the area you wish to select remains visible. This
will help you make an accurate selection. Making an accurate
selection with this tool can take a long time - but if you
want to do a good job then you may not have much choice.
To use the
lasso tool 
just drag
around the edge of the area you want to select. When you let
go of the mouse button, a line will be drawn back to the
starting point to complete the selection. Accurate use of
the lasso tool is much easier said than done however.
To use the scissors tool
just click, click, click your way around the shape you want
to select - the more clicks you make the more accurate your
selection will be but in any case the GIMP will help you by
trying to detect the edges of the shape (by looking for the
contrast between lighter areas and darker areas). Even the
scissors tool is not ideal however, for it often does a poor
job finding the edge of the shape, leaving you with a
scruffy-edged selection.
Is there no tool capable of giving a clean-edged
selection? Yes! The GIMP includes a very powerful path
tool 
which
can do this - this is the tool which we will focus on
now...
Test your selection skills by using the path tool
to select Sugar, the dolphin in the photo below. Select the
path tool in the
toolbox or press 'b' on the keyboard or choose
Tools>Paths. The path tool is so sophisticated that I
suggest you limit its power the first time you use it (you
wouldn't want to have driving lessons in a Porsche 911 would
you?). So turn on the tool's 'polygonal' option - this will
limit you to making a polygonal selection - not an obvious
move when you want to select a dolphin - but the polygon can
follow curved edges well enough if you make enough clicks.
Start clicking your way around the dolphin, then - I'm
expecting you to take your time on this and make about 40
clicks altogether. Your work will be easier if you expand
the picture to fill you screen (double-click the picture's
blue title bar then do View>Zoom>Fit Image in Widow or Ctrl+Shift+E).
If you want to zoom in further on the
dolphin then type '+' on the main keypad. Ignore the hoop as
you click your way around the dolphin. When
you get back to the beginning stop and examine the path
you have created. If you want to add additional nodes (each
point is called a node) you can, by Ctrl+clicking the path.
If you want to delete a node then Ctrl+Shift+click it. When
you have finished making the path you should convert it to a
selection by clicking the corresponding button in the
tool's option window.
What to do with our selection? Let's make it seem that
there are two dolphins jumping through the hoop at the same
time (call them Sugardaddy and Sugarbaby if you like). Duplicate your selection by simply copying it (Ctrl+C)
and pasting it (Ctrl+V). Nothing much seems to happen but
you'll know the second dolphin is there if you choose the
Move tool (press 'm' on the keyboard) and drag the dolphin
into a new position. Also, if you check the Layers window
you will see that you now have a new layer labeled 'floating
selection'. WARNING: this layer is only temporary and you
may lose it unless you take one of two actions: either
incorporate the selection into the layer below by pressing
the 'anchor floating layer' button
in the layers
window or put the selection into a 'real' new layer by
clicking the New Layer button
. The second
option is much better since it gives you more freedom to
return to the selection later and operate on it separately
to the other layers.
Let's shrink the new dolphin to make it look like mother
and baby are jumping through the hoop together. Choose the
Scale tool (or press Shift+T). You probably don't want to
change the shape of the dolphin, only its size, so hold down
the Ctrl and Alt keys as you drag a corner handle to resize
the dolphin. Press the Enter key when you have the size you
want. Switch back to the move tool (press 'm') and drag the
baby dolphin into a location such that the hoop looks
'natural'. Save your finished image in the jpeg
format (and also in the XCF format if you think you may want
to modify it later).
If you'd like to visit Sugar, he lives in Sugar Key, one
of the Florida Keys...
In this lesson you have only used
the path control with the polygon option turned on, meaning
that you were only able to create a shape with straight
sides. The next step would be to use the tool with the
polygon option turned off - each segment of the shape could
then be given a curve. This is time-consuming, however, and
a bit complicated and difficult so it is not covered in this
course. However, if you think you are ahead of your
classmates then you are more than welcome to explore the
full power of the path tool - check section 6.1 of the Gimp
help system to get started.
In this lesson we have done a
pretty good job in manipulating a photograph so that it
presents an image of something that never was. This is
deceptive, of course, and you should be starting to think to
what extent it is morally acceptable to manipulate images in
the way that I am teaching you. A few years ago there was a
scandal when two magazines used the same photo on their
covers - a photo of a suspected criminal. The scandal
happened because one of the magazines had manipulated the
photograph to make the person look more evil than he looked
in the original... Make no mistake - MANY of the photos you
see in magazines have been manipulated. Stop Press: I
just noticed that today, 12 April 2005, the BBC website is
carrying a story called 'Sacking call over doctored photo' -
the article is about how a UK Conservative party candidate modified a
photograph for political reasons, leading to calls for his
resignation. Are we playing with fire??
