How to convert a texture to grayscale?

Hi guys!
This is my problem:
I want to apply to a texture (taken from the webcam) a filter that convert the texture from color to grayscale.
I can’t understand how to do this. Can anyone suggest me the appropriate nodes to make this stuff?
I hope you can help me.
Bye.

use this pixelshader from … uhm … i forgot sorry.

change:
HueSaturation.txt
to:
HueSaturation.fx
and place it into your effects folder
then open it and connect the webcam to the texture input. with ‘value offset’ to zero you will hav ea greyscale - pic

HueSaturation.txt (6.9 kB)

hi hrovac

i took the liberty to post your shader in contributions with a help file
HueSaturation

cheers