Image is not displayed correctly, looks interpolated

[liouma]

I display a gif anim with the same resolution as my display (480x320) on a pi zero w with a GPIO screen. command : FBpyGIF -fb 1 ./happy.gif

The result is strange, it looks like an interpolation of image. As I can't describe it, here is a video and the original gif anim:

https://user-images.githubusercontent.com/106532164/202615653-1047bbee-c7ed-453e-9124-40df9ee521e8.mp4

I run python 3.9 on Debian GNU/Linux 11 (bullseye)