Let's initialize them to zero. It looks alright, but then it
also looks alright with v3, or with the corresponding pixels
from the source. I don't know what the original intent would
be, and the original effectv source also has this bug/feature.
https://bugzilla.gnome.org/show_bug.cgi?id=661841
dest[width + 3] = v3;
dest[width * 2] = v2;
dest[width * 2 + 1] = v2;
+ dest[width * 2 + 2] = 0;
+ dest[width * 2 + 3] = 0;
dest[width * 3] = v2;
dest[width * 3 + 1] = v2;
+ dest[width * 3 + 2] = 0;
+ dest[width * 3 + 3] = 0;
src += 4;
dest += 4;