How to get the icon position for items?

Hello, I am trying to find how to get the icons for the items. I know where the icons are:

GameData.pak\Libs\UI\Textures

Which contains some images like this:

the problem is how to find which icon corresponds to which item, since they are grouped in this whole image in a grid without a pattern (the icons don’t have a unique grid, they are in different spaces in the image).

Anyone can help?