I'm learning to edit photos--usually the shadow areas are too dark and the light areas O.K. or blown out.. I've been using Desaturate>Invert>Overlay, which lightens up the shadows and brings out detail, but it makes the overall colors look artificial and sort of plastic, sort of like old Kodachromes.

is there anything I do to fix this?

Thanks in advance!

You could try using luminosity masks, for examples see:

https://patdavid.net/2013/11/getting-around-in-gimp-luminosity-masks.html

There is a script to assist making the masks: http://registry.gimp.org/node/28644 It puts an entry in Filters -> Generic -> Luminosity Masks (saulgoode)

Run that and it makes a lot of entries in the channels dialogue. One way of using is, channel to selection, then adjust the selection - brightness, contrast, ....

Another way is use a layer mask. So using your image. (luminosity01)

1. Duplicate it

2. Apply the luminosity mask script

3. Add a mask to that layer, selecting a suitable channel. Black is transparent, White is opaque. To keep the sky and lighter foliage, and adjust the dark vegetation, 'D' might be a suitable choice.

Working on the duplicated image (not the layer mask), adjust using whatever tool you like, color curves is a good choice. (luminosity02)

rich: www.gimp-forum.net