This is a very good approach to make photos look more detailed and bring out more detail in the darker areas instead of using High Dynamic Range (HDR) or overexposing the highlights.
This tutorial was done with Photoshop Elements 8 but should apply to any Editing package that can do Layers, Overlay and Adjustment Layers.
First we open our underexposed, slightly darkish photo as seen below. You can see the jacket is rather dark and is missing detail as well as the girl’s face is rather contrasty.
Now in Photoshop, duplicate the layer (CMD+J on the Mac, CTRL+J on Windows) and Work with the duplicate layer. You need to completely de-saturate that layer. In order to do so, Create a new Saturation Adjustment Layer (Layer -> New Adjustment Layer -> Hue and Saturation) and pull the Saturation slider all the way to the left. You will get a black and white image (grey really).
Next, Assign that adjustment layer ONLY to apply to the Layer copy , otherwise it will affect the whole image. To do this, select the Adjustment layer and push CMD+G or CTRL+G in Windows. NOTE: Some version of Photoshop have this with CTRL+ALT+G!
Now that we have a grey layer, we need to invert it by selecting the actual Layer copy and then going to Filter -> Adjustments -> Invert. This will cause your layers and Image to look something like this:
Now we need to Gaussian blur the inverted layer, Just a little bit in order to make it a little softer later on. Go to Filters -> Blur -> Gaussian Blur and adjust by up to 5 pixels and click OK.
This is the part where you see progress. With the inverted and blurred layer selected, change its blending mode to overlay and change the opacity to something like 20-25% and all of a sudden you will see this:
You can see the colors become brighter and in the darker areas there is a little bit more detail, subtle but its a great effect that can be adjusted with the Opacity slider.
To the very last, we will need to add a little bit of contrast to adjust some of the too flat tones, simply create another Adjustment Layer, but this time a Contrast and Brightness one and then changr the contrast subtly to your liking. The finished product is different to notice but not totally blown our like HDR or highlights.
