@Wayne_Sutton
Actually i wrote that and i think it’s true.
Thank you for your participation 
Originally, 4 years ago, I wanted “Locallab” similar (in general principles) to Nikon Upoints… (the same principle we found in DxO)
Note that I was only inspired by the principle, not having the code of Nik Software.
It is based on 3 basic principles :
- deltaE betwen a reference (the Rt-spot center) ane each pixel
- in some cases a Sobel-canny to detect Structure
- a variable transition
And many parameters in Settings to adjust these 3 principles
Certainly what I present here is very simplified, but it translates the real operation, with a principle (the same as Capture NX2). You point (U point) and the software does what you want.
But, because there is many but.
First, I think, 3 years ago, to be able to see the changes made:
So 2 additions:
- show modifications
- show structure
To note, even if it looks like a mask it is not one, it is only an accentaution of the changes by changing background color and changed details.
And in 90% cases these functionnalities are more than enough
Second, 2 years ago, we ask me to add “mask”
Indeed in some cases, where the natural deltaE is not sufficient to be discriminating, mask may be usefull.
I was inspired by the principle of the masks used in color-toning (by Alberto), but change the manner to do, incorporating the functioning into that of “Upoint”
It may seem odd, see complex, but the assembly of the 2 works very well.
You can just use one mask, or a series of masks taken from each module, or duplicate Rt-spot to used several mask…as much as you want.
These masks needs of course to be seen (its obvious, but needs GUI…)
These masks have several possibilities
- mask LCH
- structure mask
- blur mask
- using a specific deltaE
Possibilities to merge add or substract to the current image
And several tools : contrast curve, gamma, chroma, slope, shadows, highlight, Laplacian, Hue curve, local wavelet contrast, etc.
These tools and possibilities are function of the level of compexity (normal…expert).
In some cases thes mask can be used after “locallab” (Tone mapping, Retinex…)whereas normally it is before.
For me, maks, add complexity, of course, when you use “Upoint” + “Mask” you have more discriminating possibilities, but this only concerns at most 10% of cases.
Obviously complexity is something relative, see what i wrote here…
Now after this tune-up it’s almost impossible just to split the GUI in half…it is the same combobox which conditions the functioning of both, and “cut in two” will complexify the code and GUI.
So it’s up to the user to make the right choices
Thank you 
Jacques