Is the Noise Filter Random?

[Richard S.]

Does anyone happen to know if the "Add Noise" filter generates random noise each time, or does it create identical noise patterns every time?

I would expect it to be random, but software has surprised me before, so always better to ask

[lepr]

You'd have known the answer immediately by performing a trivial test. 

Anyway, the noise pattern is identical every time. Same story with the Perlin Noise filter. Why a developer would make that restriction is anybody's guess.

[Richard S.]

That's why I asked, because it looks identical, but Id expect it to be randomised.

[GarryP]

The Live Add Noise Filter effect seems to be non-randomly generated starting from the same part of the document for all layers.
However, the noise in each layer will be different if those layers have different X/Y coordinates.
So, while it’s true that it’s the same every time, it’s also true that it can look different every time.
If you want to add different noise to two layers that will have the same X/Y coordinates then you could slightly offset one layer, add the noise, rasterise it, and then shift the layer back to where it was. You lose the ‘liveness’ of the result but maybe that’s okay for some purposes.
My attached video of a 10x10-pixel document shows what happens.

Adding an extra slider to the filter settings might allow us to select a different ‘randomisation’ for each use; maybe better than truly random each time as we get to control it.

[lepr]

 

1 minute ago, GarryP said:

Adding an extra slider to the filter settings might allow us to select a different ‘randomisation’ for each use; maybe better than truly random each time as we get to control it.

Yes, there should be a seed control - a slider and numeric field.