Painting Light With Overlay Layer
Photoshop CS6 Tutorial
How to Add or Remove Light with a Photoshop Overlay Layer
Layers with the Blend Mode set to Overlay can be used to add light to or remove light from selective areas of your image. By painting with white the area becomes lighter. Painting with black darkens the image.
Another way to affect the light in an image is with Adjustment layers. For an example of this technique, see topic, Selective Layer Adjustments.
Open an image in Photoshop (File > Open).
Click the Create a New Layer icon twice to add two new blank layers.
Set the Blend Mode for both layers to Overlay. Name the middle layer Darken and the upper layer Lighten.
To paint light into the image, select the Brush tool (b key), choose a soft edged brush and set the Foreground color to white.
With a lower brush Opacity, paint on the Lighten layer to lighten selective areas.
Change the Foreground color to black and paint the Darken layer to selectively remove light from the image.
Soften the Edges
Since the painted light resides on it's own layer, you can select the Lighten or Darken layer and choose Filter > Blur > Gaussian Blur. This will make the paint strokes and edges less noticeable.
Adjusting the Effect
By adjusting the Lighten or Darken layer opacity, you can adjust the intensity of the effect.