It may have something to do with Lightroom automatically working in the ProPhoto color space.
The Lightroom uses the ProPhoto RGB color space which has a much wider gamut of colors to handle however while saving to JPG you need to check which of the color profile is set during export i.e. Adobe RGB, Pro Photo RGB or sRGB.
If its sRGB it might add up some extra tint and show the file changed.
Second thing would be what happens if you see your exported pic again imported in Lightroom.
Hope this helps.
The photos that have been exported are dark and never get light again.
The exported file that I tested by re-importing it to Lightroom (Mandhir's
suggestion) remained dark. If I export a photo from Lightroom and view it
in Windows Photo Viewer, then return to Lightroom, it seems that all of the
photos in Lightroom are darker than they were before I exported a photo. If
I then close Lightroom and re-open it later, the photos there all look
lighter again. I don't normally see any difference in files when switching
between the Library and Develop modules, although some time ago there was a
difference in just one particular file. Thanks, Brett for your interest and
They look darker when viewed in Windows Photo Viewer, and when printed by a
local lab. I exported them in Adobe RGB(1998) color space.
Let’s forget about the lab... I’m a Mac guy, not sure that Windows Photo Viewer is ICC aware. Do you have Photoshop? Or Elements. What happens if you export in sRGB, closer in Windows Viewer? You really need to find another ICC color aware application to view the images and compare to LR. Even Safari Windows should do this IF you embed the ICC profile, then use it’s Open command.
Thanks, Andrew for your input. I don't have Photoshop, Elements or Safari
Windows. I'm also not sure if Windows Viewer is ICC aware. I tried
exporting a file in sRGB and viewed it in Windows Photo Viewer (when I go
to the "Pictures" folder on my hard drive and select a file, it
automatically opens in Windows Photo Viewer). You're right, I really do
need to find another app that's ICC aware. I'll work on that. Hope I'm not
wasting everyone's time with this. I sure do appreciate the help. I didn't
pick the screen name "technodunce" for nothing! [?] I DO want to learn
though, so thanks for your patience.