def thicken(image, mask=None, iterations=1):
    '''Thicken the objects in an image where doing so does not connect them
    
    0 0 0    ? ? ?
    0 0 0 -> ? 1 ?
    0 0 1    ? ? ?
    
    1 0 0    ? ? ?
    0 0 0 -> ? 0 ?
    0 0 1    ? ? ?
    '''
    global thicken_table
    if mask is None:
        masked_image = image
    else:
        masked_image = image.astype(bool).copy()
        masked_image[~mask] = False
    result = table_lookup(masked_image, thicken_table, False, iterations)
    if not mask is None:
        result[~mask] = image[~mask]
    return result
Thicken the objects in an image where doing so does not connect them
    
    0 0 0    ? ? ?
    0 0 0 -> ? 1 ?
    0 0 1    ? ? ?
    
    1 0 0    ? ? ?
    0 0 0 -> ? 0 ?
    0 0 1    ? ? ?