fopp_downscale

import image
import math
angle = 10  # we humans think degrees
angle = angle*math.pi/180  # radians

img = image.Image("golden_gate.png")
height = img.getHeight()
width = img.getWidth()

win = image.ImageWin(width, height)
img2 = image.EmptyImage(width, height)

for y in range(height):
    for x in range(width):
        r = (x**2 + y**2)**0.5
        cur_angle = math.atan(y/x) if x else math.pi/2
        orig_angle = cur_angle + angle
        orig_x = round(r*math.cos(orig_angle))
        orig_y = round(r*math.sin(orig_angle))
        if (0 <= orig_x < width) and (0 <= orig_y < height):
            orig_pixel = img.getPixel(orig_x, orig_y)
            img2.setPixel(x, y, orig_pixel)
img2.draw(win)
win.exitonclick()