After having found out by being told on Flickr that it is possible to adjust the compression of pix when saving I had a good look at Paint Shop Pro 11 and found there is also in the later series a reasonable shadows etc. lightener.
So I decided to see what could be done with Infrared pic. Used the following for the Nailsea Wall pic.

In PSP 11 select Adjust – Colour – Red/Green/Blue
In this instance
Red 62
Green –37
Blue –39

The change to Image menu select Grayscale.

Back to Adjust - Smart fix
In this instance
Overall 28
Shadows –30

Highlights 20
Saturation 99
Focus 89

I think this will work better in future than dodging between programmes.