From what I could gather, a PAL VHS picture was 576 lines but it only stored a maximum horizontal resolution of around 333 pixels. On the back of an envelope I worked out that meant that the image stored on a VHS tape had about 46.25% of the horizontal resolution of a broadcast PAL image.
Therefore, suppose the original image was this Telefusion Yorkshire one (click to see it at full size):
Before: the original 720 x 576 pixel image
Then it would be stored as this much red information (click to see at full size):
This much green information (click to see at full size):
and this much (or, rather, little) blue information (click to see at full size):
And when combined you'd get an image like this:
Incidentally, PAL images have non-square pixels. So in order to see the "before" and "after" images on this page in the correct aspect ratio I have scaled them horizontally from 720 pixels up to 788 pixels.