Gradient scaling

from PIL import Image


def get_grad_value_of_channel(first_color, second_color, index, length):
    return (first_color * (length - 1 - index) + second_color * index) / (length - 1)


def get_grad_value_of_color(first_color, second_color, index, length):
    return int(get_grad_value_of_channel(first_color[0], second_color[0], index, length)),\
           int(get_grad_value_of_channel(first_color[1], second_color[1], index, length)),\
           int(get_grad_value_of_channel(first_color[2], second_color[2], index, length)),


def main():
    filename = "/home/melon/Desktop/pic.png"
    original_image = Image.open(filename)
    original_pixels = original_image.load()
    original_image.show()
    x_scale = 5
    y_scale = 5
    scaled_image = Image.new('RGB', ((original_image.width - 1) * x_scale, (original_image.height - 1) * y_scale), "black")
    scaled_pixels = scaled_image.load()
    for x in range(original_image.width - 1):
        for y in range(original_image.height - 1):
            left_side_colors = []
            for dy in range(y_scale + 1):
                left_side_colors.append(get_grad_value_of_color(
                    original_pixels[x, y],
                    original_pixels[x, y + 1],
                    dy,
                    y_scale + 1
                ))
            right_side_colors = []
            for dy in range(y_scale + 1):
                right_side_colors.append(get_grad_value_of_color(
                    original_pixels[x + 1, y],
                    original_pixels[x + 1, y + 1],
                    dy,
                    y_scale + 1
                ))
            for dx in range(x_scale):
                for dy in range(y_scale):
                    color = get_grad_value_of_color(left_side_colors[dy], right_side_colors[dy], dx, x_scale + 1)
                    scaled_pixels[x * x_scale + dx, y * y_scale + dy] = color
    scaled_image.show()


if __name__ == '__main__':
    main()