I’m very confused and looking more for an explanation, because I can’t seem to find it on the internet.

So I want to create a simple gif of an rectangle that rotates around its center in python. The rectangle consists of alternating black and white pixels.

Now If I do that with image libraries like pillow or opencv they always need to interpolate some pixels and they become grey. I attached an image where you can see this.

Now if I do the same thing in Microsoft powerpoint, it can do a rotation perfectly. Where is the difference?

That’s the code I’m using:

frames = []
for i in range(15):
    angle = i * 15
    rotated_img = img.rotate(angle, resample=Image.Resampling.NEAREST, expand=True)

    # Create a new image with the grey background
    frame = background.copy()

    # Calculate the position to paste the rotated image
    rotated_w, rotated_h = rotated_img.size
    offset = ((background.size[0] - rotated_w) // 2, (background.size[1] - rotated_h) // 2)
    frame.paste(rotated_img, offset, rotated_img)

I was expecting no interpolation.