| In many
situations there is an object which you require, but it
is set against a background. Let's take an example of a
photograph, and the background will be extracted. The original
photograph (of me in my old office) is:
It can be seen that it is hardly the best background
for a picture which is to be used in another graphic.
I typically use the following tools in sequence:
| 
|
Lasso. To initially cut the outline of
the picture in a rough way. |
| 
|
Magic wand. To get rid of pixels around
the image. |
| 
|
Eraser. Finally I zoom-in and use the
eraser to carefully get rid of the pixels around
the object. |
A good effect is to use Alpha Transparency with a photograph,
so that it blends the picture into the background, such
as (using one of my photographs):
| |
|
Alpha
Transparency |
Index
transparency |
You can see that the index transparency has made the photograph
bring the background through wherever there is a white pixel.
One major advantage of using GIF files instead of JPEG pictures
is that JPEG does not support transparency. For example:
| |
|
GIF
(with transparent background) |
JPEG |
|
