Parametric Mask...Input vs Output Sliders...anyone care to clarify

There was a brief discussion of this on the DT Facebook page but I am not sure I have my head around it…Basically it is my understanding that in a module if you select output sliders of the parametric mask then the effect of the module is applied to the entire image first and then the mask is created from that new image and blended with the original image to produce the final effect or resulting output. If the input sliders are selected the mask is calculated from the image first before applying the module effect and then the effects are applied to the image before it is blended with the original image to produce the final image…At least I think is is how it was explained and or how I understood it. Not much in the manual and I am not sure how to explain it if both sets of sliders were selected…If any one wants to take a crack at clarifying this and why you might chose one over the other I would be interested in peoples thoughts…Additionally if you have any good references that might tackle this let me know. I need go back on YouTube to see if it was covered . I will add a reply to this post if I find a good clear answer…Thanks everyone

Hi @priort,
If remember it correctly, Bruce WIlliams did not understand it either :slight_smile:
according to one of his tutorials on the subject. I’ll try to find that reference…

Have fun!
Claes in Lund, Sweden

Harry made a video about parametric masks where he talked about output:
https://youtu.be/x1RRaXbnixQ?t=1168

As far as I understand the input is to gather the mask area and the output is to restrict the range where the effect is applied to. But I can be wrong with this interpretation.

I did watch that video but he really just says it restricts the application of the effect the the output but I am trying to understand the semantics of how that is different from choosing what is masked by the input sliders…this is a quote from the facebook group about the output sliders…" Nicolas Belleville Basically, darktable computes the output without mask. Let’s call it O1. Then, darktable computes the mask value M for each pixel using O1 and the input I. Then, it creates the real output O2 = (1-M)xI + MxO1
So, what you see on the screen is O2, O1 is just an intermediate result"