with(ImageTools):
#conversion forward
dimensions:=[upperbound(img)];
gray := Matrix(dimensions[1], dimensions[2]);
for i from 1 to dimensions[1] do
	for j from 1 to dimensions[2] do
		gray[i,j] := 0.2126 * img[i,j,1] + 0.7152*img[i,j,2] + 0.0722*img[i,j,3]:
	end do:
end do:
#display the result
Embed(Create(gray)):
#conversion backward
x:=Create(gray);
ToRGB(x);
#display the result
Embed(x);