__all__ = ['image_mutual_information']

from ants.decorators import image_method

from ants.internal import get_lib_fn

@image_method

def image_mutual_information(image1, image2):

    """

    Compute mutual information between two ANTsImage types

    ANTsR function: `antsImageMutualInformation`

    Arguments

    ---------

    image1 : ANTsImage

        image 1

    image2 : ANTsImage

        image 2

    Returns

    -------

    scalar

    Example

    -------

    >>> import ants

    >>> fi = ants.image_read( ants.get_ants_data('r16') ).clone('float')

    >>> mi = ants.image_read( ants.get_ants_data('r64') ).clone('float')

    >>> mival = ants.image_mutual_information(fi, mi) # -0.1796141

    """

    if (image1.pixeltype != 'float') or (image2.pixeltype != 'float'):

        raise ValueError('Both images must have float pixeltype')

    if image1.dimension != image2.dimension:

        raise ValueError('Both images must have same dimension')

    libfn = get_lib_fn('antsImageMutualInformation%iD' % image1.dimension)

    return libfn(image1.pointer, image2.pointer)