How I can add grayscale filter to an image

[Abudahim]

in other words, what is the algorithm of grayscale image . I knew how to invert color and other stuffs but still dont know how to make it grayscale .
thank you

 

[Divil]

http://www.bobpowell.net/grayscale.htm

 

[Hamburger1984]

maybe this article will help you, too...

http://www.codeproject.com/cs/media/csharpgraphicfilters11.asp

 

[Abudahim]

Im thankful to you Mr.divil and Mr.Hamburger1984 .
they were so helpfull .