Use Channels to select pixels based on their brightness values

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This trick lets you select pixels based on luminosity. Go to the Channels Panel (Window > Channels) then hold Cmd/Ctrl and click on the RGB channel to load the luminosity of the image as a selection (alternatively, Cmd/Ctrlclick on any other channel to load it). By selecting the brighter parts of an image, you can make precise tonal adjustments that are tailored to different parts of the tonal range. Here, after selecting the luminosity, we’ve added a Levels Adjustment Layer. When you add an Adjustment Layer while a selection is active, the selection will automatically be converted into a Layer Mask, so you can selectively adjust the tones in the isolated area. We’ve used the Levels layer here to enhance the details in the moon’s surface and add a touch of yellow.