Interesting. I hadn’t heard that term before.
From [learn.foundry.com]](Laplacian)
The Laplacian node takes the input image, applies a blur, and then subtracts the original from the blurred input to produce an image useful for edge detection or motion estimation. Apply different smoothing filters to the output to trade off between speed (box) and quality (gaussian).
So a lot like a high-pass filter How to use Highpass or grain theft?
As I do more of my work in sceneLinear now I have moved away from my obscure photoshop blend mode and almost always use blur and subtract.
The most obvious gotcha is the order of subtraction.