It was shot with a 2/3 3-CCD EFP camera, which captured 3:1 compressed 1440 x 1080 (= 1.5K)
It is a little more complicated than that. The image that camera captures is 1920 x 1080, but part of the image (I believe the Y portion) is less. But when you examine the final image, each pixel is distinct from the others. It wasn’t until the next generation (used on ROTS) that it was true 1920 x 1080 (meaning each pixel was uniquely captured and recorded instead of the partial processing the Sony HDW-F900 used). But the key thing is that the final image was 1920 x 1080 hd, not 1440 x 1080. If you research the camera, that is very clearly stated and backed up by the resulting image. And HD is not 2k. The 2k format is slightly higher resolution. After ROTS was shot, Panavision developed a lens to compress the image so the 1080 lines didn’t need to be cropped for wider images like Lucas used for Star Wars. The resolution for both AOTC and ROTS is 1920 x 816. ROTS has more color depth.