The Skill to Erase the Background

Although there are many applications can make transparent GIF, it is necessary for us to erase the background manually. It is usually a boring work. I will tell you how do I to this.

	Taking the left figure for example, it's background is not of pure color, so it can't be made to transparency directly. It must be filled with the same color before doing this. Someone may erase the background with brush tool of some graphic software, but it's too slow. For this reason, I use fill tool to erase the background. I use the application, Paint Shop Pro for example. You can use other application to do this with the same concept.
Tolerance 40	Before using the fill tool, make sure that the fill tool you are using has the feature of Color Tolerance. It means when you using the fill tool, the tool will fill the background with a new color if the neighbor pixels with similar color. Then this tool is able to handle the background with complex colors. In PSP, if you set the tolerance to be 40 and just fill the image once, you may get the left result. The fill tool automatically filled the top-right region. It's faster than brush tool.
Tolerance 80	The more color tolerance value, the bigger area filled. Be careful. If the value is too high, some area that you wish to reserve may be also filled with new color, just as the left figure. Even with the same color tolerance value, starting filling at different position in the image will cause different result. You can try several position to find out the best result.
	Repeat the previous step some times and modify the value of color tolerance suitably to make the biggest filling area, but the reserve one.
	Use pen, brush, or eraser tool to eliminate the remaining noise until most area were complete. You can adjust the size of your tool to make the operation faster.
	Zoom in the image and modify the edge of the object with small size tool, and then make this image transparent. It's OK.