Image size change

I am using a .gif image as an image icon for a button but i observe that when i do so, the size of the image seems to be changed. If i set preferred size of the button equal to the size of the image in pixel, only a part of the image comes on that button. When I tried to look a little deep into it i found that all the .gif images become big on importing them.

Why does it happen. Any solution to keep them to the same size?

[438 byte] By [new_rishia] at [2007-11-27 6:34:12]