| Where
bandwidth is limited it is sometimes a good idea to make
images as small as possible, and still be able to portray
the required information. Two of the main techniques are:
 |
To reduce the number of pixels in the graphic,
as this wastes bandwidth to display a graphic which
is scaled down. For example never use a width and
height tag in an image insert which is not equal to
the graphics' size. |
|
Reduce the number of colors in the image. |
For example the following shows four pictures taken with
16.7 million colors, 32 colors, 8 colors and 4 colors, respectively:
| |
|
16.7
million colors |
32 colors |
Even when the colors have been reduced,
you can still see that the image is of a cat. The sizes
of the files produced are 3.62KB, 2.42KB, 1.10KB and 562B.
It can be seen that reducing the number of colors in the
image has a considerable effect on the file size (and the
bandwidth used, of course, if the image is being sent over
a communications channel). The reason that the file sizes
reduce is that the file are compressed using an algorithm
which detects long sequences of the same color, and replaces
it with a special code. Thus the fewer the colors, the more
likely these sequences will occur, thus the smaller the
file size will be.
|
