Just in case that interests someone, here is a little script to reset the diffuse color/values to white/1.0 for the 'PoserSurface' root nodes of the currently selected figure:

# This sets the diffuse value/colour to 1.0/white on ALL textures of the currently selected figure
#
# Author: Y-Phil (on Renderosity)
# Version: 2021-01-17

import poser


def main():
    scene = poser.Scene()
    try:
        fig = scene.CurrentFigure()
    except:
        fig = None

    if not fig:
        poser.DialogSimple.MessageBox("Please select a figure...")
        return

    if not poser.DialogSimple.YesNo(
        "Please, confirm to reset the diffuse color/value " + 
        "in this figure's material def.:n" + fig.Name()
    ):
        return

    for mat in fig.Materials():
        root_node = mat.ShaderTree().NodeByInternalName('PoserSurface')
        if bool(root_node):
            node_input = root_node.InputByInternalName('Diffuse_Color')
            if bool(node_input):
                node_input.SetColor(1.0, 1.0, 1.0)
            node_input = root_node.InputByInternalName('Diffuse_Value')
            if bool(node_input):
                node_input.SetFloat(1.0)
        
    scene.Draw()


main()

𝒫𝒽𝓎𝓁

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