Using an expression node you can creat an ST Map using the follow equation in the red and green channel. ![[Pasted image 20220804202836.jpeg|500]] But what's up with the `+.5` ? At first I always used to put `x/width` in the Red and `y/height` in the Green. But it was brought to my attention that the STmap would ever so slightly alter my image, even if there was no transform happening. --- Here is a base STmap setup ![[Pasted image 20220806104832.jpeg]] Here is a closeup view of the checkerboard directly. ![[Pasted image 20220806104805.jpeg]] But looking at it through the STmap, with **no tranformations** yields this result. ![[Pasted image 20220806104959.jpeg]] The pixels have been offset by half a pixel. Why? From what I was told is that by default the `x/width`, `y/height` defaults the STmap into the lower left corner of the image. As seen by the red dot below. ![[Pasted image 20220806105430.jpeg]] However for the STmap to properly lineup it needs to start at the centre of the first lower left pixel. So we need to add `.5` to the X and Y which gives us: `(x+.5)/width` & `(y+.5)/height` and now our STmap will line up. Happy Days. ---