From painted vertex color attributes, create an RGB flowmap that shows the "flow" of colors

Flowmap generator.py

import bpy
import bmesh
from mathutils import Vector

obj = bpy.context.active_object
me = obj.data

# cannot access color attributes within bmesh,
# so we will create a dict of indices to access the linked edges in object mode
bpy.ops.object.mode_set(mode='EDIT')
bm = bmesh.from_edit_mesh(me)

index_to_linked_verts = {v.index: [e.other_vert(v).index for e in v.link_edges] for v in bm.verts}
bm.free()
bpy.ops.object.mode_set(mode='OBJECT')

color_attr = me.color_attributes['']
target_attr = me.color_attributes['Flow']


for v in me.vertices:
    v_col = Vector(color_attr.data[v.index].color)
    v_pos = v.co
    flow_vec = Vector()
    for adj_ind in index_to_linked_verts[v.index]:
        adj = me.vertices[adj_ind]
        adj_col = Vector(color_attr.data[adj_ind].color)
        adj_pos = adj.co
        col_len = (adj_col - v_col).length
        if col_len <= 0.001:
            flow_vec += (adj_pos - v_pos)
        else:
            flow_vec += ((adj_pos - v_pos) / (adj_col - v_col).length)
    flow_vec.normalize()
    target_attr.data[v.index].color = (flow_vec[0], flow_vec[1], flow_vec[2], 1.0)