Get Texture 2D after all shader passes are applied

Im working on a project in which I know the UV coords of a part of a 2d texture I need to sample. The problem is that if I just take the texture image file, It does not have any of the changes made by the shader, and therefore is not quite the same. the shader does not make any lighting or position specific changes, it just modifys the colors, and combines a few textures and such. What I want to be able to do is sample the colors of the texture after the shader has ran through all its passes, Kind of in the same way as in node based shader editors, how they show how each node effects the image.

Thanks in advance