getting a range in a gradient with pixel processor

poopipe

hello

I've been smashing my head against my desk all evening trying to grab a range of grayscale values in a gradient/mask using the pixel processor


I can select a "stripe"  from a gradient as a 1 bit mask easily enough  
 

I can also bash a distance node after it to get a nice gradient


what would be nice is to be able to do all that within the pixel processor. I don't want to simply work over a pixel distance  - that would be cheating and also wrong. What I'd like to do is build the gradient based on the values within the range I'm selecting (ie. normalized gradient from the matching value out to the edges of the range) 

I'm struggling with trying to normalize a float mostly - it's hard to work out what the min/max values of the whole image is when you can only look at one pixel. 
Do I need to sample in the whole image (or bits) to do this or is there a cunning way that only clever people know about?

sorry for the rambling.   has anyone done this succesfully?  i found a height slice thing on substance share but it doesn't work as elegantly as I'd like.  


ta

Jerc

I've tried doing something similar to create a more efficient autolevels node, but I don't think that's currently possible unless @NicolasW knows a way through some dark sorcery.

Bruno Afonseca

Would this work? I've done this with a pixel processor. It doesn't normalize though, unless you plug an autolevels after it:
https://share.allegorithmic.com/libraries/2569

NicolasW

I made this



here the .sbs: https://www.dropbox.com/s/fel5rzidm1z1mjm/histogram_select.sbs?dl=0

Elithenia

This is awesome!