![example picture for update_pixels()](/images/reference/Sketch_update_pixels_0.png)
```python
def setup():
img = py5.load_image("rockies.jpg")
py5.image(img, 0, 0)
half_image = img.width * img.height//2
py5.load_pixels()
for i in range(0, half_image):
py5.pixels[i+half_image] = py5.pixels[i]
py5.update_pixels()
```