SS4DarthPayne said:

The Star Wars Screenthemes pack (SEE HERE) made some available in higher resolution, but even then, there are many holes that still exist. For example, THIS picture of Luke and Darth dueling is in the ROJ storybook, and is a famous image, but try as I might, I can’t find a digital version of it in good resolution. Does anyone know where they could be found (if at all)? Or have them themselves? Good resolution images not in the Screenthemes pack are out there, and I am curious as to where they may have come from.

Many questions to answer but I'll focus on this.

Firstly, all ScreenThemes pics are cropped, original images are wider/taller that have been cropped to 1600x1200. Also McQuarrie art from the Themes have been squished.

Secondly, LFL does have all promotional photos digitalized. They have had catalogs and probably still do which I also have where are thumbnails of most promo images (but still there are slight variations of the same set as could have taken a couple of photos and you can see a slight movement between them, and also harder to find images that have not been touched up e.g. blaster bolt missing, lightsaber blades missing etc.). They could offer the catalogs to press/other media that wanted to use hires pics, and they would have to order them from LFL if they had the luxury to choose. There is the elusive Kodak Photo disc which has all these images in hires but haven't ever found it. Anyways, the only chance to get the original hires images is from press material, that's where they usually originate. "Unofficial" hires pics are scans of photos made outside LFL.