def get_conversion(scale, limits):
    """
    Get the conversion equations for each axis.

    limits: dict of min and max values for the axes in the order blr.
    """
    fb = float(scale) / float(limits['b'][1] - limits['b'][0])
    fl = float(scale) / float(limits['l'][1] - limits['l'][0])
    fr = float(scale) / float(limits['r'][1] - limits['r'][0])
    conversion = {'b': lambda x: (x - limits['b'][0]) * fb, 'l': lambda x: 
        (x - limits['l'][0]) * fl, 'r': lambda x: (x - limits['r'][0]) * fr}
    return conversion
