Select and mask based on the color on BG

[brindavin29]

Hello Team,

I have a bunch of files with different BG's where I need to automate the files to select and mask based on the predefined color in script.
EG: If BG has light grey, Mid grey & Shadow grey, script should pick any of the 2 grey values and select and mask the values within photoshop masks.

Attached the script currently what I am using which is created based on the selection area using marquee tool. But now I need it to refer the values with our pre-defined color values for masking.