This function will modify a picture to draw shadows behind mountains.
After selecting this feature you will be asked to set 2 parameters:
This is the angle in degrees where level is reference under which the light is illuminating the picture. Th licht is always positioned at the upper-left cornere.
This is the grade of black on the scale from 0% to 100% where 100% is fully black and 0% is completely transparent.
The following example is having shades with a light elevation of 10% and reduction factor of 50%.