@yotsuya: Again, I respectfully disagree.
AotC was definitely shot in 1440x800.
I think the important part is this:
Since SW2 was to be displayed as 2.35:1, and Panavision were not able to come up with the promised Anamorphics to work with a Prism-splitter 3-CCD camera, the movie was shot letterboxed, so the master images were only 1440 x (about) 800.
Lucas didn’t plan to use a HDW-F900, but a ‘Panavised’ one (HDW-F900F). But Panavision didn’t deliver in time, so Lucas had not other choice than cropping his shots.
Furthermore, HDCAM SR tape format was not yet available, so he had to use a ‘bastardized’ HDCAM 4:2:2 (instead of 3:1:1, but not SR) limited to 1440x1080.
So the final cropped shots were in 1440x800 (which is still HD).
Some other interesting quotes:
this meant that, unfortunately as is the case with digital masters in general, 1440x1080 would remain 1440x1080 until the end of Time
According to Wikipedia :
The actual resolution of Attack of the Clones is not 2k, but just 817x1440 pixels. This is because the HDCAM format subsamples the 1920 horizontal lines to 1440. The 1080p aspect ratio of the camera only applies when the 16:9 aspect ratio is used. To produce the 2.39:1 aspect ratio, the top and bottom of the image are cropped, reducing detail. This cropping is why Spy Kids 2, (shot with the same camera) looks better then attack of the clones. Spy Kids used the native 16:9 aspect ratio and thus used all the pixels of the camera. (Anamorphic lenses could have allowed the full 1080 lines to be used, but were not available for the HDW-F900.) . --Algr (talk) 19:17, 27 June 2019 (UTC)
And the final word to ILM HD Supervisor Fred Meyers himself :
With the earlier equipment, RGB color from the camera was converted into 4:2:2 YUV format when it was recorded. This format effectively slices the color bandwidth in half because one color value represents more than one pixel. The result is fewer chroma (color) samples than luma (luminance). This chroma sub-sampling combined with spatial sub-sampling effectively reduced HD’s 1920 resolution to 1440 for luma and 960 for chroma.
JEDIT: ChewieLewis is right, most of the movie is CGI, not related to HD cameras.
IIRC, CGI was rendered in 2k (so really no need to scan AotC in 4K, which is the main question here)