Magazines and books prior to the digital age almost exclusively used promo pics taken by stills photographers. That’s because they looked better than frame blow-ups from a print. The stills were processed by the marketing department and often didn’t look much like the actual scenes from the films. Even special effects shots were often specially created as promo pics and not directly from the film. There were a lot of those created for the Star Wars films. You would occasionally see frame blow ups in books or magazines focused on filmmaking, like Cinefex and American Cinematographer.
Starting in the digital age (DVDs), it became more common to see frames taken from a digital transfer (not from an actual print). But they were still subject to alterations in color by the publisher. So I really wouldn’t place much stock in those pics.
Here’s the sky from the LPP:
