from kivy.lang import Builder
from kivy.base import runTouchApp
from kivy.uix.boxlayout import BoxLayout
Builder.load_string('''
<Test>:
    Image:
        id: original
        source: ''  #insert pic
    BoxLayout:
        orientation: 'vertical'
        Button:
            text: 'Flip'
            on_release: root.flip()
        Button:
            text: 'Flipped'
            on_release: new.texture.save('test.png')
        Button:
            text: 'Raw'
            on_release: original.texture.save('test.png', flipped=False)
    Image:
        id: new
''')
class Test(BoxLayout):
    def flip(self):
        tex = self.ids.original.texture
        tex.flip_vertical()
        self.ids.new.texture = tex
runTouchApp(Test())