Channel Chops - Open Up Your Shadows

Open up an image that needs the shadows to be opened up. Click on the channel palette. And click on the RED channel.

Make a copy of the red channel, by dragging it down to the "create new channel" icon at the bottom of the channel palette.

Click on the "load channel as a selection" button at the bottom of the channel palette.

The selection will be for the high values. Invert the selection. Select / inverse. The screen will look like this.

The next step is to click on the layer palette and highlight the background layer. Then move the selection up to a layer. (Control / Command) J. Change the blending mode from normal to "Screen" and set the opacity of the layer to 30%. The layer palette should look like this
:

At this stage the shadows of the image should be opened up and show more detail without affecting the high values.

Before:

After: