Is it possible to select a tonal area in histogramm in a filter?

Software G'MIC
1

Out of curiosity. Would it be possible in Gmic to have a filter where you can chosea a tonal area by selecting a left and right point in a histogram?
How the left and right points are selected is irrelevant. Could be by clicking in the histogramm or by slideres…

2

Filters > GMIC > Lights and shadows > Slice Luminosity

already allows you to do this, be it by specifying numerical ranges…

1 Like
3

Ok thanks, that’s interesting.
And could a histogramm be displayed?
To choose tonal areas I often find a histogramm to be very useful.

4

Isn’t that what the Threshold tool effectively does?

724×753 224 KB

(Using GIMP)

5

I presumed all tonal differences within the range had to be preserved.

6

Basically yes I’d like to select a left and a right limit. This could be done with the threshold tool.

I see I need to be more specific.
I’d like to use select a tonal range. The histogram I want because I find it easy to see the edge of a tonal region in a histogram. Imagine a bright sky with a dark foreground, you can easily discern the two peaks in a histogram.
Then I want to use the selected values to do some computation using overlay layers and masks.

This is a procedure I’m experimenting with so I was wondering if this could be automated using Gmic.

7

How about -

create the layer mask from a Greyscale copy of the layer.
Use the threshold tool on the layermask
…

You may find it’s better to use the curves tool instead of the threshold tool to give you gradual transitions

8

Yes.

I think I will work my idea out a little better and do a thorough post here later. So it will be easier understand what I’m trying to accomplish.