gray scale or edge detection?

in the address bellow i have put an image for letter i.

if you see the image and magnify it, you can see extra parts or noise parts. how can i eliminate them using php. i hate Mathworks or mathlab.

i tried grays scale using imagecopymergegray(), not bad but if there is somthing better?

i used the instruction bellow:

imagecopymergegray($dimg, $simg , 0 , 0 , 0 , 0 , $currwidth, $currheight,75);

image is located here. i forgot it.