frank678 said:

I thought colour correction might be a miracle restorative but the more I understand it the information in these sources is not deep enough to stand much boosting without destroying the picture.

I was just playing around with screenshots of the '82 LD version of the Greedo scene, and you're absolutely right. Here's the original image - notice how everything looks brown and gray, including Greedo's skin:

And this is what I had to do to get the contrast and colors anywhere close to how it looked originally:

I'm surprised I was able to recover even that much. Look at the extreme white clipping on the subtitles, and the reflection on Greedo's eye. The chroma noise from the video signal is exaggerated to a ridiculous degree, especially in the walls. It reminds me a 256-color GIF image from 1995. The low contrast and high gamma of these transfers (especially in dark scenes) means that for some scenes, the image literally does have to be destroyed to even approximate the original colors.