3p

from PIL import Image, ImageDraw
import math
def create_background(size, color):
    r = color[0]
    g = color[1]
    b = color[2]

    ri = math.floor((255-r)/size[0])
    gi = math.floor((255 - g) / size[0])
    bi = math.floor((255 - b) / size[0])
    img = Image.new("RGB", size)
    pixels = img.load()
    for i in range(size[0]):
        for j in range(size[1]):
            pixels[i,j] = (r,g,b)
        r += ri
        g += gi
        b += bi
    return img