Hello Arturo
First, thank you for participating in the improvement
In fact, it is more complex, menu choices are necessarily limited. What do we fit into what ?
First of all I want to remind that at the origin of “Locallab” (4 years ago) there were no masks.
I was inspired by the interface imagined in 2006 by Nik Software, “U point” (“You point” and you have the result), with no mask (at the end Nik Software add mask, but there were hidden…)
A) original algorithm
So if we go back to the origin of my design, no masks.
I search several month and years and I found an algorithm - without masks, because the masks are not at all intuitive (at least for me) - to solve the problem of detecting shapes, in order to avoid 2 things:
- no clipping use (lasso, …)
- no layers, no blending, no mask
The algorithm uses several things to meet the goal (I simplifie):
- the notions of reference - hue, chroma, luma where is the spot - must take into account the size of the reference
- the deltaE notion : deviation between the reference and the “color” of any pixel in the image
- the transition notion : the idea of introducing a degression starting from a certain threshold
- the structure notion : as in some cases deltaE is not discriminating enough, I introduce the “structure” notion, difference between solids and structure.
In all these cases, the shape of the RT-spot is of little importance (rectangle, elipse, or others)
Resumed of action whithout mask, for me in 90% cases
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selected a Rt-spot big enough to cover the area to change and it doesn’t matter that it goes beyond
- selected (or let by default 60%) the transition value (TR) : up to TR% - geographically - of the Rt-spot area, deltaE wil be apply at 100%, after (TR% - 100%) there will be a regression to get to zero
- selected a “Scope” value : range of deltaE. At 100% no effect for deltaE, all colors are concerned, values by default about 20, must satisfied a majority of cases
Selected the action you want, lightness, chroma, contrast, graduated, local contrast, retinex, etc.
And, it is finished.
But, because the is a but, I had to improve the algorithm
- in some cases “Structure” (“Color and Light”, “Exposure”) improve the result
- allows RT-spot different from “circle” (rectangle, elipse) in some cases
- allows “Excluding spot”, to undo certain actions
- 4 sliders (in Expert mode) allows to modified “DeltaE rules” : normal Rules deltaE (dC = dL = dH and linear weakening) - see documentation
- 2 sliders (in Expert mode) allows to modified “Transition rules” - normal transition rules - linear weakening XY - see documentation (especially to touch up small defects, red eyes, etc.)
- and of course you can open multiple "Rt spot"
B) Masks
Two years ago, I was asked to add masks, inspired by what Alberto had done for “Color toning”
The first question for what to do ? certainly it is a request, probably partly because people have not completely understood the algorithm
But, it’s a request and in some cases original algorithm fails (as Nik software!),so I looked for how and why
I will resume more than one years of changes and improvment
- 2 usages for masks : a) improve selection deltaE , b) special effects
- generally in “normal” mode you have 3 curves L, C, H, a slider “blend”, a smoother, a chroma slider, a contrast curve
- for the 3 curves, you see (thanks to @Pandagrapher ) the 3 references (hue, chroma, luma)
If blend is at zero, you only improve deltaE ( a) above)
if blend > 0 or < 0, ( b above) you add or substract the mask of the original image (before threatment) - for Retinex or Tone-mapping you can choose after or before
But, when you get into the logic of masks, you have to go further. So, depending on the case and mode (expert or normal), I added other type of mask - creation of mask - others than the 3 curves LCH : Structure mask and Blur mask (in addition to LCH)
And also work on mask - Structure mask, gamma mask, slope mask, level contrast mask, Laplacian mask, shadows mask, Highlight mask, hue curve mask, dynamic range compression mask
And of course you can uses more than one mask, and more than one spot.
Of course you can see the work on the mask.
C) what to show
We realize that if we had to offer the possibility of showing all the possible choices the selection menu would be very important.
So, I limited the possibilities which at the start were :
- none - normal display
- show modifications whithout mask (we can change but for which label ?)
- show modifications with mask (we can change but for which label ?)
- show mask
- structure
About one year ago, one ask me to add “Preview selection deltaE” (someting as in Darktable)
Of course we can change the labels, but it will be difficult, not impossible to change the contents
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show modification whithout mask : use for the essantial deltaE algorithm, stucture, and transition
The grey aspects will change when you change curve, sliders, methods,…that acts on luminance, chrominance, hue, and when you change scope, transition and sliders (in settings) that acts on deltaE or transition
Mask have no action
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show modification whith mask : same as above, but take into account mask whether the slider blend is zero or not
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show mask : show the work on the current mask (you cannot show 2 masks in the same screen), blend is not active, transition is not active, deltaE has quasi no effect, deltaE mask have an effect if you uses tools mask (contrast curve, chroma, etc.)
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show structure : (when possible) - shows in grey the area concerned by structure (Sobel canny algorithm) - structure is “added” to deltaE
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preview selection deltaE : shows areas concerned by deltaE algorithm, whatever the settings on luminance, chrominance, hue. Tansition is not active, all sliders settings deltaE are actives and of course Scope
If you change sometings that acts on luminance you will see the result (side effect)
if you enable mask with (or whitout) blend you will see the changes.
I hope to have been clear
jacques