Darkening or Lightening specicfic areas of an image.
This technique can be used in most imaging software that can use layers.
1. Create a new blank layer above the image layer you wish to modify.
2. Fill this new layer with grey 128,128,128 RGB in the layer drop down menu set to Overlay
the image below will become visible.
3. Working on the Overlay layer, use a normal brush to the size you require - ideally a soft brush.
4. To start with at least set the Brush Opacity to a low percentage - say 15%.
5. To darken an area you need the brush set to Black, to Lighten an area set the brush to White.
6. Working on the new Overlay layer you will see any are on the image Darken or lighten gradually as you paint with the brush. Change the Brush Opacity/Size to suite.