[Gimp-developer] Idea: selection curve

[Stephane Chauveau]

Hello,

I just got an idea about the curve tool: Why not use it as a selection tool?

Apart from The Gimp, I do not know a lot of image manipulation programs 
so the feature might very well be common.

I see it like that:

A new tool called the 'curve selection' would be added probably in the 
Select menu.

Like the original curve tool, the 'curve selection' tool would provide 
several curves for the different properties of the current layer (see 
the list below).

The value of each curve would not provide a transformation of the 
property but an amount of selection (from 0.0 to 1.0) according to the 
property.

The result of the curve selection tool would be a selection mask 
obtained by multiplying the values of all curves.

For most curves, the initial value value would not be the identify 
function 'f(x)=x' but 'f(x)=1.0'.

The following curves could be provided:
   - Red , Green and Blue  ( default  f(x)=1.0 )
   - Hue, Saturation, Value/Lightness/Brightness  (default  f(x)=1.0)
   - Initial Selection Mask ( default f(x)=x ) 
   - Alpha (default f(x)=1.0)

With those defaults, the overall default result would be the initial 
selection mask.
 
Because of it circular nature, the Hue curve may require a specific 
treatment.