Dune (2021) and its sequel were shot and presented with IMAX-format footage for certain scenes. “IMAX ratio” refers to the taller aspect ratio used in IMAX-branded presentations (typically 1.43:1 or 1.90:1 for digital IMAX), which reveals more vertical image than the standard widescreen theatrical ratio (usually 2.39:1). For Dune, director Denis Villeneuve and cinematographer Greig Fraser used IMAX cameras for select sequences to give scenes greater vertical scale and immersion.

Let us address the elephant (or sandworm) in the room.

The short answer: Most downloads you find are illegal.

Warner Bros. and Legendary Pictures have not released a consumer disc (4K Blu-ray) that contains the variable IMAX ratio for Dune. Unlike Christopher Nolan’s films (which often include shifting ratios on disc), the Dune home releases are locked at 2.39:1.

Consequently, any torrent or direct download labeled "Dune.2021.IMAX.1080p" or "Dune.Part.Two.IMAX.2160p" is almost certainly one of three things:

Downloading these via BitTorrent or Usenet exposes you to ISP warnings, malware, and poor quality (heavy compression artifacts).

The Dune films were shot with IMAX-certified digital cameras (Arri Alexa LF/Mini LF) and feature two distinct aspect ratios:

Fan demand focuses on the 1.90:1 (easily viewable on 16:9 screens) and the rare 1.43:1 (iconic for scenes like the Gom Jabbar test or Paul’s first sandworm ride).