Resolve shadows

[fmw42]

You can try -gamma. It is a non-linear function. Try values < 1. That will give you a steep curve at the low (dark) values and a flatter curve at the higher values.

You can also try one of my scripts, PLM, CURVES, or REDIST. see http://www.fmwconcepts.com/imagemagick/index.html

PLM allows you to build your own piece-wise linear transformation. So you could process the darks and keep the lights unchanged. CURVES is similar but generates an interpolated curve rather than linear sectons. Both allow you to simulate -gamma or create your own approximate curved transformation as you would like to have it.

REDIST attempts to modify the histogram to give it a bell shape. You will just need to define a mean value and a standard deviation value for the low and high side of the bell curve.

You could also try RETINEX as well from my scripts. It can bring detail out of shadows.

[anthony]

It sounds you are wanting to use a HDRI technique (without HDRI) so that you can brighten the grass but not the sky.

An altrunative trick is to generate a mask and then use that to brighten just one area of the image.