Local Contrast - can it have a threshold feature?

Labels added: Type-Enhancement
Labels removed: Type-Defect

Originally reported on Google Code with ID 1931

I've found the Local Contrast tool to be very useful for adding more "pop" to low-contrast
images.  However its effectiveness is reduced as if there is a high-contrast area of
the low-contrast image, this will have its contrast raised too high.  

I hope this can be seen in the images uploaded here http://filebin.net/bdjxofkyb4 
The photo is pretty low-contrast, but when the local contrast is increased, it burns
out the area of sky above the people at the top of the steps, and turns the top peoples'
heads black.  

Would it be possible to add in a threshold feature, similar to that for USM and Vibrance,
which would enable the local contrast to be prevented from affecting high-contrast
transitions?  

The uploaded images are 3 of the same photo but with different values of Local Contrast,
the CR2 file and the pp3 file.  

Version info:

Branch: default
Version: 4.0.11.8
Changeset: 171b81f84a0f
Compiler: gcc 4.7.1
Processor: 1
System: Windows
Bit depth: 64 bits
Gtkmm: V2.22.0
Build type: RELEASE
Build flags:   -fopenmp -O3 -DNDEBUG -mthreads -funroll-loops
Link flags:   -mwindows -s
OpenMP support: ON
MMAP support: ON

Operating system in Windows 7 64-bit with 8GB RAM.

Reported by christopher@geela.co.uk on 2013-07-21 16:04:27

Beep6581 / RawTherapee

Local Contrast - can it have a threshold feature? #1915