| |
May
7 , 2000
Exporting GIFs
Creating
background and anti-aliased transparent GIFs
Ever wonder how to get the best out of
FreeHand's GIF export? How to create tileable background GIFs or even
transparent, anti-aliased GIFs? Well these series of tips will certainly
help with the mysteries.
I first have to express my gratitude to
Ken Kehl and David Gangwisch (FreeHand's SQA Engineer)
for helping me understand how FreeHand exports GIF files with transparencies.
I can tell you this, the manual sure didn't help much and if you were
as confused as me, you'll want to thank those guys too.
Version: 8 and above
|
|
| |
 |
|
Above is some art I'm going to be
exporting in this series of tips. The logo is all vector art in
FreeHand as well as that background shape. The
background pattern is actually a Tile filled rectangle consisting
of a bunch of lines.
This is basically a comping piece
to show what the logo would look like on the background. Once
the client is happy, we can now make this art ready for the web.
The main purpose of this exercise
is to export both pieces as separate GIFs. The logo will be made
transparent and will be anti-aliased to the yellow color that
falls behind it.
|
Tileable Background
GIFs
 |
|
This is the part that I used to
create that Tile fill. It's a simple rectangle containing a blend
of two yellow lines. If you've created such a fill, then all you
need is the starting piece like shown above.
While this piece is selected, go
to the File menu and Export.
|
 |
|
Select the GIF format and
turn on the option Selected objects only (only if you have
other objects in your document).
Next click the Options button
to see more options available. Choose 72 dpi, anti-aliasing
at 2-3 and turn off the Include alpha channel options.
In the More options area I chose
these (they may be different for your art):
-
Interlaced turned on
-
Dither: None
-
Palette: WebSnap Adaptive 16
-
Optimized Palette turned on
|
|
|
|
The results are what you see above.
The table cell is set to have this background pattern in it so
it repeats seamlessly.
The tag will look something like
this:
<TD BACKGROUND="/images/background.gif">
So that's how you create background
tileable GIFs. Easy enough eh? Now on to the really fun stuff.
|
Transparent Anti-Aliased
GIFs
 |
|
Now we're going to export the logo
so that it works with that background. The reason we need to make
it transparent, is so you don't have to be exact when placing
it on your HTML document.
First I'll show you what happens
with just a regular GIF export with no anti-aliasing. Then I'll
show how to fix that so it looks great!
With the logo selected, go to the
Export dialog again.
|
 |
|
We'll use nearly the same export
options as before, only this time we'll turn on the Include
alpha channel option.
In the More options area I chose
these:
-
Interlaced turned on
-
Dither: Moderate
-
Palette: WebSnap Adaptive 128
-
Optimized Palette turned on
-
Transparent Background turned
on
|
|
|
|
The results are what you see above.
As you can see, while the background of the GIF is transparent,
the edges of the text and the logo shape are all jagged. This
is not what I had in mind, and I'm sure the client wouldn't be
happy.
FreeHand automatically uses the
non-object areas of the page as an alpha mask. With the GIF, however,
you need to provide a color for the transparency edges to anti-alias
to.
So how do you get around this? Well
remember seeing that option Alpha includes background?
Now we are going to put it to use.
|
 |
|
Select all the art you want to anti-alias.
Clone this and it might be a good idea to put this on a
new layer to keep from changing the original art.
Now give everything a thick Stroke.
If any of the art doesn't have any stroke, then give it one. This
includes Text (for more on giving text a stroke, see the tip Giving
Text an Outline in the Tips Archive).
Then place this cloned art behind
the original art and check if the strokes are thick enough to
see. In my example above, I recolored the strokes green so I could
see what was going on.
Generally you want to make sure
the strokes are a couple of points thicker than the original art.
Once you are happy with the thickness, recolor the strokes to
White.
|
 |
|
Now you want to create a rectangle
filled with Black behind this white clone. This can be
any size.
The reason we are doing this is
how FreeHand uses the Background as an Alpha channel. Anything
Black will be masked out or transparent, while anything white
will be solid.
|
 |
|
If you placed this cloned art on
a new layer, just move that layer to the background area of the
Layers palette (below the separator). If not, then just move the
art to the default Background layer.
It should now appear screened back
like shown above.
|
 |
|
Now since we want to anti-alias
to that background pattern, we will create a solid block of color
behind the logo. This is based on the most dominant color of the
pattern... yellow. This rectangle also acts as the bounding area
for the size of the final GIF.
Now off to the Export dialog again.
|
 |
|
Use the same export options as before,
only this time we'll turn on the Include alpha channel
and the Alpha includes background options.
In the More options area I chose
these:
-
Interlaced turned on
-
Dither: Moderate
-
Palette: WebSnap Adaptive 128
-
Optimized Palette turned on
-
Transparent Background turned
on
|
 |
|
Above is the final results. As you
can see, the edges are perfectly anti-aliased to the yellow color,
seen as a slight yellow halo around the edges. This "halo"
was defined by that white, thick stroked clone you created and
put on the background.
|
|
|
|
Once placed on the final background
pattern, it looks fantastic!
Of course you can adjust the halo
size by decreasing or increasing the point size of the White colored
clone you created.
|
|
WARNING
|
|
If you noticed that your background
objects are now opaque, you are experiencing a bug. This is
explained in more detail in the Troubleshooting section under
the Background Layers Become Opaque topic.
|
While this isn't the most time effective
way of creating GIFs of this sort, at least you know how to accomplish
it without the use of any other outside applications. This is especially
nice if you don't have a lot of memory to open multiple applications
such as PhotoShop or Fireworks.
|
|