Amiga Computing - Commodore Is Awesome

This month fry
doing a drop
shadow or two -
Neil Mohr shows
you how
If you have been following what is
admittedly, o fairly basic tutorial, you
should at least now be familiar with
iHH all Phoiogenics' mos: regulcrly used
parts: Drawing tools, alpha channel and com
posite function. This month we ore going fo pull
all these elements together and actually do
something useful - add a drop shadow.
This is a fairly simple technique, but drop
shadows are used absolutely everywhere. In
magazines - there are more than likely a few in
this very magazine. On Web sites - drop shad
ows are almost compulsory, the Amiga
Computing site is no exception and they also
turn up on television. The reason being they
help emphasise an element by making it literally
jump off the poge or screen, adding a sense of
depth.
For this example we will be using the space
man tutorial image, which luckily already has
an olpho clip outline ready for us to use, which
Is handy. This alpha image will act as the basis
for the shadow and will also allow us to pre
pare the spaceman image as well as tidying up
the final product.
After you have loaded the spaceman image
and its alpha clip, the first thing to do is touch
up the alpha image so it is ready for use. The
main changes are whiting out the rest of the
planet and adding the detail for the spaceman's
foot. The best way is to use the rectangle tool to
white out most of the earth, then switch to either
Cliff and
his drop
shadows
the polygon or freehond tool and clean up the
left over bits.
For the fine detail on the foot, paint on ihe
original image covering the spaceman's feel and
then select the alpha as the actual alpha chan
nel, you can slowly add or remove the black
area until you have a good match to the origi
nal. To tidy up the final shadow use the blur
draw tool to anti-alias the new foot section you
have added.
Once all that is out of the way you can get on
with creating the parts of the final image. The
first step is to gel the spaceman seporaled from
the rest of the picture. As we have the alpha
channel ready to go, just fill the spaceman
image with black and fix these changes, leaving
o spaceman suspended in blackness.
Before making the shadow for the spaceman,
create a clone of the existing alpha channel
which will be used later. To create a proper
shadow effect perform a gaussion blur on the
entire olpha image - it's best to use the gaussion
blur option from the image menu. Set it to about
six and sit back and twiddle your thumbs or bet
ter still go make a cup of tea - for some reason
Photogenics' gaussian blur is about as fast as a
snail on Mogadon.
Now we have our shadow image and main
spaceman image ready to be composed
together. Select the spaceman picture as the sec
ondary image and make the shadow image that
is currently the alpha, the primary image.
PlFF, PAFF, PUFF INSTANT SHADOW
First atop is to got hold ol all the images you need to
put the drop shadow together. Next, (ouch up the
alpha image by cutting out the rest of the earth
Amiga Computing
MARCH 1997
Remember you con use the one, two and three
keys as shortcuts. Select ihe shadow image and
press the right Amiga and k keys to start the
composition.
Make sure the transparent black lick box is set
and you should see your spaceman appear over
your shadow. To increase the effect you need to
offset the spaceman image slightly. Entering
minus five into both the x and y offset text boxes
should position the spaceman correctly.
Before you press the OK button take a care
ful look at the fop left parts of the spaceman, a
bit jaggy is it not? We are not going to stand
for any botch jobs, no sir're definitely not, Click
on cancel and we shall turn our attention to ihe
copy of the original alpha channel we mode.
Select it as the alpha channel, go back to the
shadow image and go to the composile
requester making sure both the transparent
black and compose alpha tick boxes are
selected.
All that should be visible now is an odd out
line of the spaceman over the shadow (this is
because the alpha is negative of what we
need). From the alpha menu use the invert
alpha option to invert the alpha channel and
Bob's your uncle - a much cleaner looking ver
sion of whot we had before. As the compose
alpha option is ticked it is moved and scaled
right along with the secondary image, so allow
ing o gentle blending into the background
colour to be applied.
Once you havo what will be shadow image, make a copy
of it, as the spare alpha. You can then cut out the spaceman
image and run a gaussian blur over the shadow