# Inverting a Mask



## Photographe (Mar 27, 2011)

I have a small area of a picture selected as a mask, and now I want to invert the selection in order to work on the rest of the photo.  There must be an easy way to do this, but I cannot find it.  Does anyone know how to do this?


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## Brad Snyder (Mar 27, 2011)

I understand what you mean in general, but how specifically have you selected a portion? With brush strokes?

Lr can't do a mask inversion like pixel editors can. You have to think in terms of applying a global effect, and then reversing it with opposite local adjustments, (or vice versa  ).


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## Photographe (Mar 27, 2011)

Brad,

I made the mask with Adjustment Brush.  I thought of using your method, but it did not work in this case. For example, apply -100 Saturation globally and then try to bring Saturation up locally.  It did not work for me.  Same with sharpening, noise reduction etc.  Am I missing something?  Inverting maks is baby stuff.  Is it really possible that it's not available?  Is it available in ACR, would you happen to know?


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## Brad Snyder (Mar 27, 2011)

Don't know about ACR, but I wouldn't think so.

Try the saturation(and others) a different way. Rather than a global change, paint -100 with a very big brush over the whole image, then bring back the selected areas with a more detailed brush.

It used to be that globally taking saturation to zero, and then bringing it back up locally presented a mathematical conundrum, akin to dividing by zero, but I thought that that had been addressed since. Right this second, I've got the 3.3 release uninstalled, and the 3.4RC sitting in the queue to install, so I can't test it.


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## Photographe (May 1, 2011)

It seems that a different algorithm is used globally vs. locally.  I ended up doing what I wanted to do using U Point in Nikon Capture NX2 (still evaluating, but so far so good). 

As far as inverting a mask goes, Capture One just announced that they have that function, so it should be a matter of time before LR follows along.  Capture One introduces such things for free in dot releases though.


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## ukbrown (May 1, 2011)

I think this is one of those sort of edits that may be best done in a pixel editing package.  TBH I have never found LR that good at doing masses of local brush adjustments


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