How do I use an Area Mask to subtract an area from a Parametric/Delta E mask?

I’m sure there’s a simple answer to this but I can’t seem to figure it out.
Once I’ve created a parametric or delta E mask, I sometimes want to use an area mask to subtract (exclude) an area from the other mask. When I use the Subtract option in the Area mask, it seems to subtract all of the previous mask, not just the part within the area mask.

I can achieve what I want using the Add option and placing the area mask over the area I want to include. But is there a way to use an area mask to exclude, or am I just going about this the wrong way?
Maybe I don’t really understand how the Subtract and Intersect options work…

see here: ART (the software) news

what you can do is to use two shapes in your area mask: one that covers the whole image (in normal mode), and another one to subtract (in subtract mode). Here’s a quick demo:

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Thanks! Ok, I’ve got it to work, but I see that it’s important to do things in a certain order and that you need two area masks. What I was originally doing was editing the “pre-made” area mask that seems to be always on. When you edit that (e.g. reduce its size to only cover a certain part of the image) and set it to subtract, it doesn’t leave the other mask active. Is this by design?

When I added a second instance of an area mask (as you did in the video), it also automatically creates an area mask that covers the whole image. So when I set it to subtract, before editing its size, it would cancel the effect of the underlying parametric/delta E mask. That was throwing me off.

I’m not sure if it’s just me, but I’d prefer the area mask to not automatically create a mask when it’s enabled. I’d prefer to start it from scratch and draw it on manually.

I’ve added up/down buttons to reorder the list of shapes in the area mask. Those indeed were missing.