Bake Vertex Colors

bake_vertex_colors.py

import bpy

bl_info = {
    'name': 'Bake Vertex Colors',
    'author': 'Tamas Kemenczy',
    'version': (0, 1),
    'blender': (2, 6, 1),
    'location': 'View3D > Specials > Bake Vertex Colors',
    'description': 'Bake the active uv texture image to vertex colors',
    'category': 'Mesh'
}

def bake_vertex_colors(obj):
    uv_texture = obj.data.uv_textures.active
    colors = obj.data.vertex_colors.new(uv_texture.name)
    pixels = list(uv_texture.data[0].image.pixels)

    for face_index, face_uv in enumerate(uv_texture.data):
        image_width, image_height = face_uv.image.size
        face_color = colors.data[face_index]
        uv_coords = (face_uv.uv1, face_uv.uv2, face_uv.uv3, face_uv.uv4)
        if (len(face_uv.uv) == 3):
            uv_coords = uv_coords[:3]

        for uv_index, uv_coord in enumerate(uv_coords):
            x = int(uv_coord.x * image_width) % image_width
            y = int(uv_coord.y * image_height) % image_height
            offset = (y * image_width + x) * 4

            r = pixels[offset + 0]
            g = pixels[offset + 1]
            b = pixels[offset + 2]

            setattr(colors.data[face_index], 'color%i' % (uv_index + 1), (r, g, b))

        face_uv.image = None

class BakeVertexColors(bpy.types.Operator):
    bl_idname = 'mesh.bake_vertex_colors'
    bl_label = 'Bake Vertex Colors'
    bl_options = {'REGISTER', 'UNDO'}

    @classmethod
    def poll(cls, context):
        obj = context.active_object
        return (obj and obj.type == 'MESH')

    def execute(self, context):
        bake_vertex_colors(context.active_object)
        return {'FINISHED'}

def menu_func(self, context):
    self.layout.operator(BakeVertexColors.bl_idname, text='Bake Vertex Colors')

def register():
    bpy.utils.register_module(__name__)
    bpy.types.VIEW3D_MT_object_specials.append(menu_func)

def unregister():
    bpy.utils.unregister_module(__name__)
    bpy.types.VIEW3D_MT_object_specials.remove(menu_func)

if __name__ == "__main__":
    register()