Windows Photo Viewer - one-by-one VS slideshow...the colors change!

Interesting finds on the way Images are processed to look different in WPV - thanks for that info.

Google's Picasa is still around in V.3.9 - Picasa - It does a similar range of things like slideshows and image by image as in WPV, but it is a total image organizer if you want - and will back up images to Google Drive cloud storage, I think, and has a range of image modification effects, transforms, and other manipulations. Free to use.

Crazy - after having downloaded from the link above, and installed and opened Picasa I get taken here:

What's happening to Picasa Picasa Web Albums? - Picasa and Picasa Web Albums Help

Of which the gist is Picasa is retired - it will work but is unsupported, so possibly a no-go -sorry - while in the background it is busy cataloging all my pictures hmpf!

Too bad about Picasa - people like it. Now that I understand about the embedded profile not being read by some programs (MPV Slideshow it seems!), I feel much better! At least the 10s of 1000s of JPEGs I've saved with photoshop are not ruined...and the free and easy FastStone is running slideshows a-ok with decent color.

So thanks to all who participated, for walking with me down this particular path. See you next time I get stuck!