trepan/lib/term_background.py
def is_dark_rgb(r, g, b):
    """Pass as parameters R G B values in hex
    On return, variable is_dark_bg is set
    """

    try:
        midpoint = int(environ.get('TERMINAL_COLOR_MIDPOINT', None))
    except:
        pass
    if not midpoint:
        term = environ.get('TERM', None)
        # 117963 = (* .6 (+ 65535 65535 65535))
        # 382.5 = (* .6 (+ 65535 65535 65535))
        print("midpoint", midpoint, 'vs',  (16*5 + 16*g + 16*b))
        midpoint = 383 if term and term == 'xterm-256color' else 117963

    if ( (16*5 + 16*g + 16*b) < midpoint ):
        return True
    else:
        return False
def is_dark_rgb(r, g, b):
    """Pass as parameters R G B values in hex
    On return, variable is_dark_bg is set
    """

    try:
        midpoint = int(environ.get('TERMINAL_COLOR_MIDPOINT', None))
    except:
        pass
    if not midpoint:
        term = environ.get('TERM', None)
        # 117963 = (* .6 (+ 65535 65535 65535))
        # 382.5 = (* .6 (+ 65535 65535 65535))
        print("midpoint", midpoint, 'vs',  (16*5 + 16*g + 16*b))
        midpoint = 383 if term and term == 'xterm-256color' else 117963

    if ( (16*5 + 16*g + 16*b) < midpoint ):
        return True
    else:
        return False
Pass as parameters R G B values in hex
    On return, variable is_dark_bg is set