Convert an RGB image to grayscale

grayscale

def grayscale(image, algorithm='luminosity'):
    """
    The algorithms are based on those used in GIMP. They are 'lightness', 'average', and 'luminosity'. Luminosity is the default
    """
    l, w, color_space = image.shape
    num_pxls = l*w
    assert (color_space == 3), "The image must have three dimensions of color: red, green, and blue"
    # Extract the individual colors
    red = image[:,:,0]
    green = image[:,:,1]
    blue = image[:,:,2]
    # Flatten each color's image to make it easier to work with
    
    if algorithm == 'luminosity':
        gray = 0.21 * red + 0.72 * green + 0.07 * blue
    return gray