Add a Filmic Glow Effect in Photoshop

A popular look in film is to add a soft glow effect. This can be done in Photoshop to give your images a stylised finish very simply and very quickly.

Here is an image with the effect applied:

Before

After

To achieve this look here are the steps:

Make a copy of your background layer. Using the keyboard shortcut of Cmd (Ctrl) + Alt + J lets you copy the layer, name it and specify the blend mode in one go. Choose Screen for the blend mode.
This will make your image look dramatically different, but the effect is too harsh and we need to add some Gaussian Blur. (Filters > Blur > Gaussian Blur.) For this image, I chose a 5px blur but this will vary and depend on both the image and image size.
Lower the layer opacity to around 50%.
Select your background layer again and create a second copy using the Overlay blend mode.
Add Gaussian Blur (I used 3.5px) and lower the layer opacity to 40%.
Move your Overlay layer to the top of the layer stack. The position of your layers in the stack will give you a different look.

Layer Order

Play with opacity and blur amounts to suit your image. You can also push this further by adding a little grain or noise to a 50% gray layer, set to overlay, with reduced opacity.

Another variation on this effect can be achieved by using the Photoshop Diffuse Glow filter with these settings: