how to do make gradient

create_gradient.py

from scipy.interpolate import griddata
import numpy as np
import Image as PILImage

def create_gradient(size, geometry):
    """
    :param size: [x, y]
    :param geometry:
            {
                "right_top: {
                        "coord": [x, y],
                        "color": '#FFF',
                        },
                "left_top: {
                        "coord": [x, y],
                        "color": Color('#FFF'),
                        },
                "right_bottom: {
                        "coord": [x, y],
                        "color": 'red',
                        },
                "left_bottom": {
                        "coord": [x, y],
                        "color": [r, g, b],
                        },

            }

    :return:
    """


    width, height = size

    grid_x, grid_y = np.mgrid[0:width, 0:height]

    points = np.array([
        geometry['right_top']['coord'],
        geometry['right_bottom']['coord'],
        geometry['left_bottom']['coord'],
        geometry['left_top']['coord'],
    ])

    result_channels = []
    colors = [
        Color(geometry['right_top']['color']),
        Color(geometry['right_bottom']['color']),
        Color(geometry['left_bottom']['color']),
        Color(geometry['left_top']['color']),
        ]

    for channel_color in ['red', 'green', 'blue']:
        values = np.array(map(lambda c: getattr(c, channel_color + '_int8'), colors ))
        grid_z2 = griddata(points, values, (grid_x, grid_y), method='cubic')
        pil_layer = PILImage.fromarray(grid_z2)
        result_channels.append(pil_layer.convert("L"))

    imRGB = PILImage.merge('RGB', result_channels)
    return imRGB


if __name__ == '__main__':
    geometry = {
        "right_top": {
            "coord": [0, 0],
            'color': '#F00',
        },
        "left_top": {
            "coord": [999, 0],
            'color': '#000',
        },
        "right_bottom": {
            "coord": [0, 999],
            'color': '#000',
        },
        "left_bottom": {
            "coord": [999, 999],
            'color': '#FFF',
        },

    }
    create_gradient(size=[1000, 1000], geometry=geometry).show()