Here’s a little Python snippet that finds out where image clips are plugged in.

mat = Application.Dictionary.GetObject("Sources.Materials.DefaultLib.Scene_Material")

images = mat.Shaders(0).ImageClips
for img in images:
	for p in img.GetShaderParameterTargets():
		print img.Name + " : " + p.fullname

This script will print out this:

# noIcon_pic : Sources.Materials.DefaultLib.Scene_Material.Image.tex
# sss_lightmap_clip : Sources.Materials.DefaultLib.Scene_Material.SkinSSS.light

for this render tree: