Color Thresholding - Color space


Hello all,

I have a question regarding changing colour space. I am currently experimenting with image analysis and am now trying to write a script to automate my analysis. I was wondering if someone could point me in the direction of what happens in terms of code when I use an RGB image and change the colour space to Lab. The Image in the window does not change i.e. doesn’t get converted to a Lab image. You can change the threshold based on Lab values and the histograms for the colour channels change. So my question is what is actually happening? Am I getting the pixels from the RGB image based on Lab values?

Also, I am developing my script in python and running it via Fiji, my coding skills are relatively beginner.