How to get threshold values from histogram(LAB)?

how to get threshold values from histogram i don’t want to use editor

get_histogram(). It returns a list per channel.

If you want to get the lab values of a specific color then
place the object infront of the camera,
drag with your mouse the region of interest on the frame buffer
and see all the values below the frame buffer.
Then you can write them down and use them to your application.