clear_background_image.py

import iterm2
import sys

async def main(connection):
    app = await iterm2.async_get_app(connection)
    session = app.current_terminal_window.current_tab.current_session
    change = iterm2.LocalWriteOnlyProfile()
    change.set_background_image_location("")
    await session.async_set_profile_properties(change)

iterm2.run_until_complete(main)

set_background_image.py

import iterm2
import sys

async def main(connection):
    app = await iterm2.async_get_app(connection)
    session = app.current_terminal_window.current_tab.current_session
    change = iterm2.LocalWriteOnlyProfile()
    change.set_background_image_location(sys.argv[1])
    # ASPECT_FIT is "Scale to fit the space, adding letterboxes or pillarboxes if needed. Does not distort."
    change.set_background_image_mode(iterm2.BackgroundImageMode.ASPECT_FIT)
    change.set_blur(False)
    change.set_blend(1)
    await session.async_set_profile_properties(change)

iterm2.run_until_complete(main)