Reducing Noise
Noisy images are annoying. One way to reduce noise is through the
channels. Copy the background layer by pressing Control/Command +
J, switch to the Channels palette, and select the channel that shows the
least noise. Drag that channel down to the “New Channel” icon (next to the
trash can) and go to Stylize → Find Edges. Then apply a Gaussian Blur with
a radius of about 3 pixels.
Look at this copy of the red channel.
Click on the new channel’s miniature icon while holding the Control/
Command key to select the content. Activate the “RGB channel” (top-most),
and switch back to the Layers palette. When the duplicated background is
selected, click on the “Add Layer Mask” icon.